INTELLECTUM VIRTUS

ELECTRICAL ENGINEERING

GLOSSARY OF TERMS

DEFINITIONS & FORMULAE

A

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A

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A

Adaptive Differential Pulse Code Modulation A

Compression technique that encodes only the difference between sequential samples and differs from a DPCM by varying the step size to reduce the required bandwidth for a given signal-to-noise ratio.

Add / Drop Multiplexer A

Synchronous transmission networks carrying multiple channels use this device to prioritise data by inserting (add) or removing (drop) lower-data-rate channel traffic from the higher-rate aggregated channel.

Advanced Configuration and Power Interface A

Industry-standard specification, co-developed by Hewlett-Packard, Intel, Microsoft, Phoenix and Toshiba, for operating-system-directed power management for laptop, desktop, and server computers.

Advanced Power Management A

Power management standard for computers that provides five power states: Ready, Stand-by, Suspended, Hibernation and Off.

Aliasing A

A/D Conversion, utilises the Nyquist principle, which states that the sampling rate must be at least twice the maximum bandwidth of the analogue signal. If the sampling rate is insufficient, then higher-frequency components are “undersampled” and appear shifted to lower-frequencies and are known as aliases. The frequencies that shift are sometimes called “folded” frequencies as the spectral plot appears folded to superimpose the higher frequency components over the sub-Nyquist portion of the band.

Alternating Current A

Form of electrical power in which the flow of electric charge changes polarity each half-cycle of a sinewave. Electric power is distributed in this form as high voltage transmitted through power lines reduces the power lost as heat due to resistance of the wire, then at the residence, the voltage is reduced.

Discovered by Nicola Tesla, 1886

Alternating Current A

Form of electrical power in which the flow of electric charge changes polarity each half-cycle of a sinewave. Electric power is distributed in this form as high voltage transmitted through power lines reduces the power lost as heat due to resistance of the wire, then at the residence, the voltage is reduced.

Discovered by
Nicola Tesla, 1886

American Wire Gauge A

Known as the Brown & Sharpe wire gauge, is a standardised wire gauge system in use since 1857, beginning in North America, then adopted throughout the world for standard measures for the diameters of round, solid, nonferrous, electrically conducting wire. The cross-sectional area of each gauge is essential in determining its current-carrying capacity.

Invented by Joseph Rodgers, 1857

American Wire Gauge A

Known as the Brown & Sharpe wire gauge, is a standardised wire gauge system in use since 1857, beginning in North America, then adopted throughout the world for standard measures for the diameters of round, solid, nonferrous, electrically conducting wire. The cross-sectional area of each gauge is essential in determining its current-carrying capacity.

Invented by
Joseph Rodgers, 1857

Ampacity A

Measured in Amperes, A and is a measurement of the maximum amount of electric current a conductor or device can carry before sustaining irreversible deterioration and is defined by operating temperature, insulation, conductor resistance, current frequency and the ability to dissipate heat.

Discovered by Arthur Edwin Kennelly, 1895

Ampacity A

Measured in Amperes, A and is a measurement of the maximum amount of electric current a conductor or device can carry before sustaining irreversible deterioration and is defined by operating temperature, insulation, conductor resistance, current frequency and the ability to dissipate heat.

Discovered by
Arthur Edwin Kennelly, 1895

Ampere A

Ampere, A

SI Base Unit

Electric Current, I

SI Base Quantity

This unit of electric current (1 amp) is the flow capacity of the electric charge in one coulomb over a duration of one second. One coulomb is equivalent to the charge of 6.242×10¹⁸ electrons.

Formally, as defined in 2014:
“The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1m apart in vacuum, would produce between these conductors a force equal to 2 × 10⁻⁷ newton per metre of length.”

Proposed:
“The ampere, A, is the unit of electric current; its magnitude is set by fixing the numerical value of the elementary charge to be equal to exactly 1.602 17X × 10⁻¹⁹ when it is expressed in the unit A·s, which is equal to C.”

Discovered by André-Marie Ampère, 1820

Ampere A

Ampere, A

SI Base Unit

Electric Current, I

SI Base Quantity

This unit of electric current (1 amp) is the flow capacity of the electric charge in one coulomb over a duration of one second. One coulomb is equivalent to the charge of 6.242×10¹⁸ electrons.

Formally, as defined in 2014:
“The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1m apart in vacuum, would produce between these conductors a force equal to 2 × 10⁻⁷ newton per metre of length.”

Proposed:
“The ampere, A, is the unit of electric current; its magnitude is set by fixing the numerical value of the elementary charge to be equal to exactly 1.602 17X × 10⁻¹⁹ when it is expressed in the unit A·s, which is equal to C.”

Discovered by
André-Marie Ampère, 1820

Ampere-hour A

Measurement of the current capacity or rate of usage of an electrical supply, in Ampere-hours, Ah and describes the use of one amp of current, flowing for a duration of one hour or 3,600 coulombs.

Amplifier Classes A

Class A: Simplest type of amplifier, whereby the output transistors conduct (without fully turning off) irrespective of the output waveform of the signal and is typically associated with high linearity and low efficiency.

Class AB: Combining “Class A” and “Class B” amplifiers, results in a more efficient amplifier, yet requires further improvement to lower distortion by biasing both transistors so they conduct when the signal approaches zero. This improves the individual component amplifiers with smoother transistors transitions in “Class B”. The “Class A” element of a small signal, initiates both transistors, until a large signal is present, then return to the alternating transistors, commanding each half of the waveform.

Class B: Output transistors will only conduct during half (180 degrees) of the signal waveform. To amplify the complete signal, one transistor is used to conduct for positive output signal and the another for the negative output. Efficiency is improved over the “Class A” Amplifier, yet still retains high distortion due to a transition point where the two transistors are turned on to off.

Class C: Switching amplifiers, with transistors on for less than a half cycle and are required for short pulses, a trigger. “Class C” amplifiers are very efficient as the transistors are off most of the time and when on, they are in full conduction. They deliver high distortion for use in filtration, often in RF circuits, where tuning circuits can restore the original signal and reduce distortion.

Class D: Producing an output of a switching waveform, at high frequency, the low-pass filtered, average value of this waveform contours to the actual required audio waveform producing a highly efficient amplifier by capitalising on the component characteristics, such as the low resolve of the linear aspect of output transistors and ensuring switching is fully on or fully off, removing linear issues.

Class G: Similar in design to “Class AB” amplifiers with an improvement in the use of two or more supply voltages.
As a cascade of select voltages, low signal levels are comparable to the appropriate amplification voltage and proportionately increasing or decreasing as per the signal, maintaining optimum performance without inefficient loss of current, pronounced in other classes of amplifier.

Class H: Modulation of supply voltages to the output devices of the amplifier, maintains a supportive mimic relationship to the signal waveform, never exceeding the signal swing. By reducing the dissipation across the output devices, the amplifier operates as an optimised “Class AB” efficiency irrespective of the output level. The key defining aspect of this amplifier is the predictive nature of the supply voltage and the excessive components to predict this.

Amplitude Modulation A

Method of transmitting information via a radio carrier wave by the amplitude (signal strength) of the carrier wave being varied in proportion to the waveform being transmitted.

Invented by Reginald Fessenden, 1900

Amplitude Modulation A

Method of transmitting information via a radio carrier wave by the amplitude (signal strength) of the carrier wave being varied in proportion to the waveform being transmitted.

Invented by
Reginald Fessenden, 1900

Analogue A

Refers to signals, circuits and systems that are natural and not digitally translated as in speech or the amplification of waveforms from past radio or television transmissions.

Analogue Front End A

Analogue portion of a circuit which precedes A/D conversion.

Angstrom A

1 Å = 10-10 m = 0.1 nm = 100pm

Annular Ring A

Conductive material surrounding a hole drilled in a printed circuit board, used for pads, vias and mounting holes.

Invented by Paul Eisler, 1943

Annular Ring A

Conductive material surrounding a hole drilled in a printed circuit board, used for pads, vias and mounting holes.

Invented by
Paul Eisler, 1943

ANSI Code A

Microsoft Windows Characters that are native and non-Unicode. ANSI Windows code pages were based on drafts, intended for ANSI (American National Standards Institute), yet labelled by the Internet Assigned Numbers Authority and denoted as “Windows-number”.

Anti-aliasing A

A/D conversion, uses a low-pass filter to remove signal components above the Nyquist frequency by anti-aliasing (eliminating) the sampled replicas (aliases) in the baseband.

Apparent Power A

Product of voltage times current in a circuit containing reactances and measured in volt-amps (VA). Practical loads have resistance, inductance, and capacitance, so both active and reactive power will flow to real loads. Apparent power is the magnitude of the vector sum of active and reactive power, which is the product of the root-mean-square of voltage and current.

Discovered by Paul Boucherot, 1820

Apparent Power A

Product of voltage times current in a circuit containing reactances and measured in volt-amps (VA). Practical loads have resistance, inductance, and capacitance, so both active and reactive power will flow to real loads. Apparent power is the magnitude of the vector sum of active and reactive power, which is the product of the root-mean-square of voltage and current.

Discovered by
Paul Boucherot, 1820

ASCII Code A

American Standard Codes for Information Interchange. Principally developed as a telegraph code, a commercial seven-bit teleprinter code, then remodelled as the ASCII standard in 1960, with the American Standards Association, which is now the American National Standards Institute (ANSI) X3.2 subcommittee. First edition published in 1963, with major revisions during 1967, and maintains the latest revision from 1986.

Originally based on English, ASCII encodes 128 specified characters into seven-bit integers as shown by the ASCII chart with ninety-five (printable) encoded characters: digits 0 to 9, lowercase letters a to z, uppercase letters A to Z, punctuation symbols, and 33 non-printing control codes.

Asymmetric Digital Subscriber Line A

When enabling internet over existing telephone lines, an ADSL modem with a filter will split frequencies to allows for a single telephone to be used for an internet connection and voice calls, at the same time. The bandwidth of a telephone line is divided into 26.075 kHz to 137.825 kHz for upstream communication and 138 kHz to 1,104 kHz, for downstream communications of ADSL and ADSL 2. The current ADSL 2+ connection has an extended bandwidth of 138 kHz to 2,208 kHz.

ADSL: ITU G.992.1 standard for Broadband Internet with an Upstream Rate of 1.0 Mbits/s and Downstream Rate of up to 8.0 Mbits/s.

ADSL 2: ITU G.992.3 standard for Broadband Internet with an Upstream Rate of 1.3 Mbits/s and Downstream Rate of up to 12.0 Mbits/s.

ADSL 2+: ITU G.992.5 standard for Broadband Internet with an Upstream Rate of 1.4 Mbits/s and Downstream Rate of up to 24.0 Mbits/s.

Asynchronous Transfer Mode Management A

Standard for the carriage of a complete range of voice, data, and video signals” and was developed to unify telecommunication and computer networks and to handle high-throughput data traffic and real-time, voice and video.

The reference model maps to the three lowest layers of the ISO-OSI reference model: network layer, data link layer, and physical layer and is the core protocol used for public switched telephone network (PSTN) and Integrated Services Digital Network (ISDN), but will be replaced in favour of all IP.

ATM uses asynchronous time-division multiplexing, and encodes data into small, “fixed”-sized packets (ISO-OSI frames) called cells, whereas the Internet Protocol (Ethernet) uses “variable”-sized packets and frames.

Automatic Gain Control A

Circuit that modulates an amplifier’s gain, in response to the relative strength of the input signal, in order to maintain the output power.

Automatic Power Control Institute A

Pre-amplification of output waveforms in power and audio systems are monitored to identify overmodulation and to reduce the amplification of that signal to a previously sampled approximation to maintain a constant output.

Avalanche Photo Diode A

Designed to take advantage of avalanche multiplication of photocurrents to provide gain. As reverse-bias voltage approaches the break-down voltage, hole-electron pairs are created by absorbed photons, acquiring sufficient energy to create additional hole-electron pairs when they collide with ions, effectively amplifying the signal.

B

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B

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B

B Field B

B, is the symbol for magnetic flux density (magnetic field), as in “B-field” is defined by the direction and magnitude (strength), and is represented as a vector field.

There are two distinct fields denoted by the symbols B and H, where H is measured in units of amperes per meter (A⋅m−1) and B (SI Measure) in teslas (T) and newtons per meter per ampere (N⋅m−1⋅A−1) and is commonly defined in terms of the Lorentz force it exerts on moving electric charges.

Bandwidth B

Continuous set of peak frequencies that range between upper and lower frequencies, measured in hertz, and may be referred to as the passband bandwidth: differential between the peak upper and lower frequencies of a band-pass filter, a communication channel, or a signal spectrum. A low-pass filter or baseband signal is where the bandwidth is equal to its highest upper frequency.

There are two distinct fields denoted by the symbols B and H, where H is measured in units of amperes per meter (A⋅m−1) and B (SI Measure) in teslas (T) and newtons per meter per ampere (N⋅m−1⋅A−1) and is commonly defined in terms of the Lorentz force it exerts on moving electric charges.

Battery Backup B

Microprocessors supervisory circuits maintain power to safeguard volatile memory and when switching between power supplies, dependence on a fully charged backup battery can be the only solution to storing operational variables and constants that would otherwise be lost. When problems occur, it is generally a result of component failure due to age or transient events that also effect backup batteries. Always replace batteries before retrieving data.

Battery Seal B

Modern microprocessors are equipped with battery implementation systems within supervisory circuits that disconnects a backup battery from any down-stream circuitry until power is applied the first time, preserving battery life.

Becquerel B

Becquerel, Bq

SI Derived Unit

Activity re Radionuclide

SI Derived Quantity

s^-1

SI Base Expression

This unit is defined as the activity of a quantity of radioactive material in which one nucleus decays per second and is equivalent to an inverse second, s⁻¹.

Named after Antoine Henri Becquerel

Becquerel B

Becquerel, Bq

SI Derived Unit

Activity re Radionuclide

SI Derived Quantity

s^-1

SI Base Expression

This unit is defined as the activity of a quantity of radioactive material in which one nucleus decays per second and is equivalent to an inverse second, s⁻¹.

Named after
Antoine Henri Becquerel

Bias B

Method of fixing voltage or current at particular points throughout an electronic circuit, providing known operating conditions within electronic components.

Binary B

Numbers expressed as a base-2 numeral system of two different symbols, 0 and 1. In digital electronic circuitry, the state of a switch may be on or off and translates perfectly for logical gates and computer-based devices.

Discovered by Gottfried Wilhelm Leibniz, 1701

Binary B

Numbers expressed as a base-2 numeral system of two different symbols, 0 and 1. In digital electronic circuitry, the state of a switch may be on or off and translates perfectly for logical gates and computer-based devices.

Discovered by
Gottfried Wilhelm Leibniz, 1701

Binary Coded Decimal B

Binary representation of a decimal number. Each decimal digit (0-9) is encoded in binary using four bits per decimal digit. This BCD value of 0101 1000 is 58 in decimal.

Discovered by Gottfried Wilhelm Leibniz, 1701

Binary Coded Decimal B

Binary representation of a decimal number. Each decimal digit (0-9) is encoded in binary using four bits per decimal digit. This BCD value of 0101 1000 is 58 in decimal.

Discovered by
Gottfried Wilhelm Leibniz, 1701

Bipolar B

Components, circuits and devices, capable of using two polarizations, such as a transistor with positive and negative charge carriers or waveforms that oscillate between two polarities.

Bit B

The symbol b, represents for the binary digits of 0 or 1, is the basic units of information in computing and digital communications. These two values can also be interpreted as logical values, true/false, yes/no, on/off or any other two-valued attribute.

Invented by John Wilder Tukey, 1948

Bit B

The symbol b, represents for the binary digits of 0 or 1, is the basic units of information in computing and digital communications. These two values can also be interpreted as logical values, true/false, yes/no, on/off or any other two-valued attribute.

Invented by
John Wilder Tukey, 1948

Bit Error Rate B

Errors occur within data streams, generally as a result of interference or noise within the digital transmission. Expressed as a percentage or a ratio, the number of bit errors divided by the number of bits transferred during a specific time interval, is the measure of the bit error rate.

Bit Oriented Code B

Data that is analysed by a communications protocol that sees the transmitted data as an opaque stream of bits with no meaning and control codes are defined in terms of bit sequences instead of characters.

The Bit Oriented Protocol transfers data frames regardless of frame contents, allowing data frames with an arbitrary number of bits and allows for character codes with an arbitrary number of bits per character.

Blade Server B

Server chassis that holds a multitude of modular motherboards of which each, dedicated blade server is built with a standard footprint, optimised for applications, network activity, power consumption and temperature. These computer systems share a back plane to address maximum use of space for large-scale computing centres.

BlueTooth B

Wireless devices capable of short range voice and data connections allow for mobile and stationary devices to communicate, via a profile, that the device must interpret settings to control communications from the start and with no line or device negotiation involved, communications become effective immediately.

Comparison of Bluetooth Adapters starting with V1.0 & V1.1 with a data rate of 768 Kbit/s, V1.2 at 1Mbit/s, V2.0 at 3 Mbit/s, V3.0, V4.0, V4.1 at 24 Mbit/s and V4.2 at 60Mbits/s.

Boolean B

Systems of logical thought benefit from a Boolean search of an “and” operator between two words such as, “apple” AND “orange”, resulting in searching for documents containing both words, not just one. With an “or” operator, “apple” OR “orange”) will result in documents containing either word. Logic, used to describe memory locations or states of a circuit that are charged (1) or not charged (0) and can use an AND gate or an OR gate.

TRUTH TABLE

(0) AND (0) = (0) OR (0) = (1) AND (0) = 0
(0) OR (1) = (1) AND (1) = (1) OR (1) = 1

Invented by George Boole, 1948

Boolean B

Systems of logical thought benefit from a Boolean search of an “and” operator between two words such as, “apple” AND “orange”, resulting in searching for documents containing both words, not just one. With an “or” operator, “apple” OR “orange”) will result in documents containing either word. Logic, used to describe memory locations or states of a circuit that are charged (1) or not charged (0) and can use an AND gate or an OR gate.

TRUTH TABLE

(0) AND (0) = (0) OR (0) = (1) AND (0) = 0
(0) OR (1) = (1) AND (1) = (1) OR (1) = 1

Invented by
George Boole, 1948

Bootstrap B

Output of a step-up converter to drive a main power FET switch, providing more gate drive than the input can supply alone. It is also a circuit whereby part of the output of an amplifier stage is applied to the input, so as to alter the input impedance of the amplifier.

Break-Before-Make B

Design of switches and relays that are required to break (open) one set of contacts before engaging (closing) another set, ensuring isolation of both signal paths.

Broadband B

Bandwidth that can carry multiple voice, video, or data channels simultaneously and distributed to household via coaxial, optical fibre, radio or twisted pair. Internet access, telephone and a multitude of CATV channels are predominantly on one coaxial cable. Made possible by frequency-division, each channel is modulated to a different frequency band and combined in the transmission medium. Then at the receiving end, it is demodulated to its original frequency and separated by guard-bands, which are empty spaces to ensure that each channel will not interfere with its neighbours.

DOCSIS 1.0 has 38 Mbits/s Down and 9 Mbits/s Up

3.09 Percent
|

DOCSIS 2.0 has 38 Mbits/s Down and 9 Mbits/s Up

3.09 Percent
|

DOCSIS 3.0 has 152 Mbits/s Down and 108 Mbits/s Up

12.38 Percent
|

DOCSIS 3.1 has 1,000 Mbits/s Down and 500 Mbits/s Up

81.43 Percent
|

Brownout B

Condition whereby a voltage drop falls below the nominal operating range, but remains above 0V. In an electrical power supply system, this condition may be enacted to reduce load in an emergency and prevent a power outage, known as a blackout.

Built In Self Test B

Mechanism facilitating a machine to test itself, meeting design requirements for reliability, repair cycles, self-calibration and operational augmentation for conditional changes.

Burst Dimming B

Controlling the brightness of cold cathode fluorescent lamps (CCFL) by turning the lamps on and off at a rate faster than the human eye can detect, nominally 100Hz to 300Hz. Higher ratios of on and off time will cause the lamps to become brighter.

Burst Mode B

High-speed data-transfer is made possible by exclusively prioritising processor and IO tasks to increase data rates. DMA controller and IO device are given exclusive access to the bus without interruption and allows cache to throughput with the CPU without consultation to the secondary memory, the RAM and to be free of handling device interrupts and dedicate resources to maximising IO throughput.

Bus B

Common paths connecting a number of devices with power as in voltage rails, or in data as in PCI and PCI Express Bus on a motherboard or heatsinks commanding thermodynamic control over temperature distribution.

Byte B

B, the symbol for the grouping of binary bits is commonly expressed as eight digits, representing 256 states of information as characters, starting from 00000000 (Binary 0) to 11111111 (Binary 255).

Invented by Werner Buchholz, 1956

Byte B

B, the symbol for the grouping of binary bits is commonly expressed as eight digits, representing 256 states of information as characters, starting from 00000000 (Binary 0) to 11111111 (Binary 255).

Invented by
Werner Buchholz, 1956

C

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C

Cable Ethernet C

Delivery of information (data packets) to recipients (devices) within a group (network) is performed through a medium (cable). The following list comprises of copper conductors that have an electromechanical interface through a network card:

Transfer Rate Performance

Category 1 1 Mbit/s 1 MHz

Category 2 4 Mbit/s 4 MHz

Category 3 10 Mbit/s 16 MHz

Category 4 16 Mbit/s 20 MHz

Category 5 100 Mbit/s 100 MHz

Category 5e 1 Gbit/s 1 Gbit/s

Category 6 10 Gbit/s 250 MHz

Category 6a 10 Gbit/s 500 MHz

Category 7 10 Gbit/s 600 MHz

Category 7a 10 Gbit/s 1 GHz

Category 8 40 Gbit/s 2 GHz

Cable Ethernet C

Delivery of information (data packets) to recipients (devices) within a group (network) is performed through a medium (cable). The following list comprises of copper conductors that have an electromechanical interface through a network card:

Transfer Rate Performance

CAT 1 1 Mbit/s 1 MHz

CAT 2 4 Mbit/s 4 MHz

CAT 3 10 Mbit/s 16 MHz

CAT 4 16 Mbit/s 20 MHz

CAT 5 100 Mbit/s 100 MHz

CAT 5e 1 Gbit/s 1 Gbit/s

CAT 6 10 Gbit/s 250 MHz

CAT 6a 10 Gbit/s 500 MHz

CAT 7 10 Gbit/s 600 MHz

CAT 7a 10 Gbit/s 1 GHz

CAT 8 40 Gbit/s 2 GHz

Candela C

Candela, cd

SI Base Unit

Luminous Intensity, J

SI Base Quantity

This unit of electric current (1 amp) is the flow capacity of the electric charge in one coulomb over a duration of one second. One coulomb is equivalent to the charge of 6.242×10¹⁸ electrons.

Formally, as defined in 2014:
“The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1m apart in vacuum, would produce between these conductors a force equal to 2 × 10⁻⁷ newton per metre of length.”

Proposed:
“The ampere, A, is the unit of electric current; its magnitude is set by fixing the numerical value of the elementary charge to be equal to exactly 1.602 17X × 10⁻¹⁹ when it is expressed in the unit A·s, which is equal to C.”

Capacitance C

When two conductors are separated by an insulator (dielectric) electrical charge is stored as capacitance, C and is an apportionment, or multiple of, a farad (F).

Discovered by Henry Cavendish, 1771

Capacitance C

When two conductors are separated by an insulator (dielectric) electrical charge is stored as capacitance, C and is an apportionment, or multiple of, a farad (F).

Discovered by
Henry Cavendish, 1771

Capacitive Reactance C

XC = – 1 / ωL = -1 / 2 π ƒ C

This measurement of a capacitor’s opposition to alternating current (AC) is similar to resistance. This value is dependent on the frequency, f, of the electrical signal affected by this capacitor and the opposition, in the form of a counter electromotive force (cemf). The Capacitive Reactance XC (Ω for Ohms) is inversely proportional to sinusoidal signal frequency ƒ or angular frequency ω (Hz for Hertz) and the capacitance C (F for Farad).

Discovered by George Ashley Campbell, 1899

Capacitive Reactance C

XC = – 1 / ωL = -1 / 2 π ƒ C

This measurement of a capacitor’s opposition to alternating current (AC) is similar to resistance. This value is dependent on the frequency, f, of the electrical signal affected by this capacitor and the opposition, in the form of a counter electromotive force (cemf). The Capacitive Reactance XC (Ω for Ohms) is inversely proportional to sinusoidal signal frequency ƒ or angular frequency ω (Hz for Hertz) and the capacitance C (F for Farad).

Discovered by
George Ashley Campbell, 1899

Charge Coupled Device C

One of two types of image sensors used in digital cameras. As the CCD is struck by light that has traversed through the camera lens, millions of tiny pixels that make up the CCD, have converted the light into electrons. At each pixel, the accumulated charge is measured and converted to a digital value by an analogue-to-digital converter (ADC), then saved as a native Raw file.

Invented by Steven Sasson, 1975

Charge Coupled Device C

One of two types of image sensors used in digital cameras. As the CCD is struck by light that has traversed through the camera lens, millions of tiny pixels that make up the CCD, have converted the light into electrons. At each pixel, the accumulated charge is measured and converted to a digital value by an analogue-to-digital converter (ADC), then saved as a native Raw file.

Invented by
Steven Sasson, 1975

Charge Injection C

Analogue switches, turning on and off, produce a small charge with capacitive coupling from the digital control line to the analogue signal path.

Charge Pump C

Power supplies that use capacitors to store and transfer energy to the output, often stepping the voltage up or down, are able to transfer charge from one capacitor to another, under the control of a regulator and switching circuitry.

Circuit C

The simplest form of a circuit is a loop connection of a power source and light bulb. With wire, safety fuse and switch, circuit protection and control systems are created. With transistors, resistors and capacitors, an oscillator will flash the light bulb. Counting flashes by way of light dependent resistor through a transistor to a single chip processor…

Circuit design elements of infinite complexities are not impossible. With the invention battery, Allessandro immersed two electrodes into water and produced hydrogen and oxygen and created the first circuit.

Discovered by Allessandro Volta, 1799

Circuit C

The simplest form of a circuit is a loop connection of a power source and light bulb. With wire, safety fuse and switch, circuit protection and control systems are created. With transistors, resistors and capacitors, an oscillator will flash the light bulb. Counting flashes by way of light dependent resistor through a transistor to a single chip processor…

Circuit design elements of infinite complexities are not impossible. With the invention battery, Allessandro immersed two electrodes into water and produced hydrogen and oxygen and created the first circuit.

Discovered by
Allessandro Volta, 1799

Clock Data Recovery C

Extracts a clock signal from an incoming data stream to facilitate the receiving circuit to decode the transmitted symbols. High-speed serial data streams are sent without an accompanying clock signal, as the receiver generates a clock from an approximate frequency reference, and then phase-aligns the clock to the transitions in the data stream with a phase-locked loop.

Code Division Multiple Access C

Digital cellular technology uses spread-spectrum techniques and unlike GSM, CDMA does not assign a specific frequency for each user, every channel uses the full available spectrum with individual conversations encoded with a pseudo-random digital sequence.

Coherent Sampling C

Describes the sampling of a periodic signal, where an integer number of its cycles fits into a predefined sampling window. A specific Fast Fourier Transform (FFT) algorithm computes the Discrete Fourier Transform (DFT) of a sequence or its inverse, then converts this original signal to a modified representation.

Colour Subcarrier C

A modulated carrier, added to a television signal, to carry the colour components. In NTSC television, a 3.579’545 MHz colour subcarrier is quadrature-modulated by two colour-difference signals and added to the luminance signal. The PAL television standard uses a subcarrier frequency of 4.433’62 MHz.

Column-Address-Strobe C

Signal notifying DRAM to accept a given address as a column-address. RAS is the Row-Address-Strobe to select a bit within the DRAM.

Common-Mode Signals C

Identical signal components on both the + and – inputs of an amplifier is an example of a balanced pair, where a noise voltage is induced in both conductors. In an ideal differential amp, the common-mode element is cancelled out, since the differential (+ and -) inputs should subtract out the identical components. A measurement of the actual ability to do this is called the Common Mode Rejection Ratio, or CMRR.

Comparator C

Device that accepts two analogue inputs, compares, then produces a binary output that is a function of which input is higher. If the non-inverting (+) input is greater than the inverting (-) input, then the output goes high. If the inverting (-) input is greater than the non-inverting (+) input, then the output goes low.

Comparator Propagation Delay C

Two or more independent comparators with consideration to the individual gate propagation delay, which is when the input duration of a logic gate becomes stable, to the time that the output logic gate becomes stable. Reducing gate delays in digital circuits allows for faster data processing rates and overall performance, as is the major contributor of glitches within asynchronous circuits.

Complementary Metal-Oxide
Semiconductor C

Fabrication methods for constructing integrated circuits as used within microprocessors, microcontrollers and a host of memory, sensors and control components. The important characteristics of CMOS devices are high noise immunity and low static power consumption with minimal waste heat as compared to TTL logic.

Discovered by Frank Wanlass, 1964

Complementary Metal-Oxide
Semiconductor C

Fabrication methods for constructing integrated circuits as used within microprocessors, microcontrollers and a host of memory, sensors and control components. The important characteristics of CMOS devices are high noise immunity and low static power consumption with minimal waste heat as compared to TTL logic.

Discovered by
Frank Wanlass, 1964

Conductor C

The ability of a conductor to allow the flow of electrons of which is the reciprocal of resistance. Measured in Siemens (S), the formula for conductance, G is equal to: G = Current (I) / Voltage (V) = 1 / resistance.

Discovered by Stephen Gray, 1729

Conductor C

The ability of a conductor to allow the flow of electrons of which is the reciprocal of resistance. Measured in Siemens (S), the formula for conductance, G is equal to: G = Current (I) / Voltage (V) = 1 / resistance.

Discovered by
Stephen Gray, 1729

Coulomb C

Coulomb, C

SI Derived Unit

Electric Charge, Amount of Electricity

SI Derived Quantity

A·s

SI Base Expression

This base unit of electrical charge is equal to 6.25 X 10¹⁸ electrons. Named for Charles Coulomb, the French physicist who pioneered research into magnetism and electricity, whom also formulated Coulomb’s law which states that the force of attraction or repulsion between two charged bodies is equal to the product of the two charges and is inversely proportional to the square of the distance between them.

Named after Charles Augustin de Coulomb

Coulomb C

Coulomb, C

SI Derived Unit

Electric Charge, Amount of Electricity

SI Derived Quantity

A·s

SI Base Expression

This base unit of electrical charge is equal to 6.25 X 10¹⁸ electrons. Named for Charles Coulomb, the French physicist who pioneered research into magnetism and electricity, whom also formulated Coulomb’s law which states that the force of attraction or repulsion between two charged bodies is equal to the product of the two charges and is inversely proportional to the square of the distance between them.

Named after
Charles Augustin de Coulomb

Crowbar Circuit C

Power supply protection circuit that rapidly short-circuits (“crowbars”) the supply line if the voltage and/or current exceeds defined limits. In practice, the resulting short blows a fuse or triggers other protection, effectively shutting down the supply. It is usually achieved by an SCR or by a mechanical shorting device.

Current C

The rate of flow of electrons through a conductor or component; measured in amperes. The symbol (I) stands for intensity of the electron flow (current), measured in Amps (A).

Discovered by André-Marie Ampère, 1820

Current C

The rate of flow of electrons through a conductor or component; measured in amperes. The symbol (I) stands for intensity of the electron flow (current), measured in Amps (A).

Discovered by
André-Marie Ampère, 1820

Cyclic Redundancy Check C

Check values calculated from the data, to catch most transmission errors as a decoder calculates the CRC for the received data, compares it to the CRC that the encoder calculated, which is then appended to the data. A mismatch indicates that the data was corrupted in transit. Depending on the algorithm and number of CRC bits, come CRCs contain enough redundant information that they can be used to correct the data.

D

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

D

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

D

Daisy Chain D

Method of propagating signals along a bus of which devices are connected in series, passing the signal from one device to the next. This daisy chain scheme permits assignment of device priorities based on the electrical position of the device on the bus.

Debounce D

Electrical contacts, as in mechanical switches, relays or contactors, often make and break contact several times before continuous conduction is achieved. A debouncing circuit will this ripple and provides a clean transition.

Decibel D

Method for specifying the ratio of two signals. The dB = 10 times the log of the ratio of the power of the two signal = 20 times the ratio of their voltages, if the signals are driving equal impedances. Decibels describe a signal level by comparing it to a reference which is defined as 0dB which is 10 times the log of the signal power over that reference.

Degrees Celsius D

Degrees Celsius, °C

SI Derived Unit

Celsius Temperature

SI Derived Quantity

K

SI Base Expression

Celsius, historically known as centigrade, is a scale and unit of measurement for temperature. From 1744 to 1954, 0 °C was defined as the freezing point of water and 100 °C was defined as the boiling point of water, both at a pressure of one standard atmosphere with mercury being the working material. Absolute zero, the lowest temperature possible, is defined as being precisely 0 K and −273.15 °C.

Named after Anders Celsius

Degrees Celsius D

Degrees Celsius, °C

SI Derived Unit

Celsius Temperature

SI Derived Quantity

K

SI Base Expression

Celsius, historically known as centigrade, is a scale and unit of measurement for temperature. From 1744 to 1954, 0 °C was defined as the freezing point of water and 100 °C was defined as the boiling point of water, both at a pressure of one standard atmosphere with mercury being the working material. Absolute zero, the lowest temperature possible, is defined as being precisely 0 K and −273.15 °C.

Named after
Anders Celsius

Delta-Sigma Converter D

ADC architecture of Delta-Sigma consists of 1-bit ADC filtering circuitry which oversamples the input signal to performs noise-shaping and achieve a high-resolution digital output and is also known as a Sigma-Delta Converter.

Design For Testibility D

Design techniques which make products easier to test and are included in the manufacturing process. Examples include the addition of test points, parametric measurement devices, self-test diagnosis and test modes.

Differential Signalling D

Most electrical signals are single-ended with a single wire and ground connection. Differential signals use two wires, inverse of each other, when one swings positive, the other swings negative in equal magnitude.
The receiving circuit will look at only the difference between the two, ignoring any common-mode voltage. This method reduces the impact of electrical interference, as external noise will affect both wires equally and the common-mode rejection will ignore the noise. Examples include the RS-422, RS-485, signal lines employed by Ethernet standards and the twisted-pair analogue telephone (POTS) line.

Direct Current D

Power source with current continually flowing in the same direction is known as direct current. Alternating current can be rectified to maintain the same current flow by use of a full bridge rectifier or alternatively, a direct current supply may be converted into alternating current by use of an inverter.

Discovered by Allessandro Volta, 1799

Direct Current D

Power source with current continually flowing in the same direction is known as direct current. Alternating current can be rectified to maintain the same current flow by use of a full bridge rectifier or alternatively, a direct current supply may be converted into alternating current by use of an inverter.

Discovered by
Allessandro Volta, 1799

Direct Digital Synthesis D

Method for digitally generating analogue waveforms, such as sine waves. Digitised samples of waveforms are stored with values that are clocked out to a D/A converter. Translation values, as in the clock rate, will change the frequency and changes to gain will modulate the signal.

Direct Memory Access D

Allows hardware subsystems to access main system memory (Random-access memory), independent of the central processing unit (CPU). When a CPU uses a programmed input/output, it instructs the DMA controller to carry out the transfer, and receive an interrupt upon completion. Most hardware operates with DMA, relieving pressure from processors and include intra-chip data transfers, disk drive controllers, graphics, network, and audio devices.

Direct Sequence Spread Spectrum D

Transmission technology used in a Wireless LAN, WLAN, whereby transmissions at the sending station is combined with a higher data-rate bit sequence, or chipping code, that divides the user data according to a spreading ratio.

Down Converter D

Device in digital signal processing, that converts a band limited signal to a lower frequency signal, preserving all information in the original signal less mathematical rounding errors and principally consisting of a direct digital synthesizer (DDS) and a low-pass filter (LPF).

Drain D

One of the three terminals of a Field Effect Transistor, FET. A voltage on the gate controls the current flow between the source and drain.

Drypack D

Method for packing electronic components, in particular, integrated circuits as the device is baked and immediately sealed in a vacuum-sealed bag. Part numbers with D, +D, or #D at the end, denote products with treated by this packaging process.

Dual Modulus Prescaler D

Important circuit block used in frequency synthesizers to divide the high-frequency signals from a Voltage Controlled Oscillator, VCO, to a low-frequency signal by a predetermined divide ratio, either N+1 or N, controlled by a swallow counter. This low-frequency signal is then further divided by the main counter to the desired channel-spacing frequency which is then fed to the phase detector to form the closed feedback loop in frequency synthesizers.

Dual Tone Multiple Frequency D

Signalling method developed by Bell Labs for sending telephone dialling information over the same phone line with each digit encoded as the sum of two sine wave bursts, of different frequencies and this two-tone method is reliably distinguished from voice.

Duplex D

Duplex is a communication channel provides simultaneous data transfer in both directions. Half Duplex is a The data transmission over a single communication channel is in either direction but not simultaneously.

Duty Cycle D

Ratio of Pulse Width to Period, indicating the percentage of time a pulse is present during one cycle, and expressed as a percentage or a ratio. D = Duty Cycle, PW = Pulse Width (Active Time) and T = Total Signal Period. D = PW/T × 100%

E

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

E

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

E

Effective Series Resistance E

Resistive component of a capacitor’s equivalent circuit, as modelled as an ideal capacitor in series with a resistor and inductor, resistor value is the ESR.

Electrically Controlled Birefringence E

Controller of optically anisotropic materials, which are birefringent, an optical property of materials with a refractive index dependent on the polarization and propagation direction of a light source.

Electricity E

Physical phenomena arising from electrons moving from a higher to lower potential level within an atom, providing electrical energy and is the science of the behaviour of electrons and protons through a conducting medium, the presence and flow of electric charge, lightning, static electricity, electromagnetic induction, power generation and transmission and electromagnetic radiation.

Discovered by Benjamin Franklin, 1752

Electricity E

Physical phenomena arising from electrons moving from a higher to lower potential level within an atom, providing electrical energy and is the science of the behaviour of electrons and protons through a conducting medium, the presence and flow of electric charge, lightning, static electricity, electromagnetic induction, power generation and transmission and electromagnetic radiation.

Discovered by
Benjamin Franklin, 1752

Electro-Absorption Modulator E

Semiconductor device that is used for modulating the intensity of a laser beam via an electric voltage, taking advantage of the “Franz-Keldysh” effect, which changes the absorption spectrum caused by an applied electric field, in turn changing the bandgap energy.

ElectroMotive Force E

Measured in volts, V, it is the force or electrical pressure that has the potential to cause electron flow in a circuit, also called voltage, potential difference or difference of potential.

Discovered by Michael Faraday, 1830

ElectroMotive Force E

Measured in volts, V, it is the force or electrical pressure that has the potential to cause electron flow in a circuit, also called voltage, potential difference or difference of potential.

Discovered by
Michael Faraday, 1830

Energy Harvesting E

Known as power harvesting or energy scavenging, it is the process in which energy is captured from an environment and converted into usable electric power which allows for electronics to operate where there is no conventional power source and enabling the device to be self-sufficient which would generally include circuitry to charge an energy storage cell, manage power, filtration, regulation, remote monitoring and protection. Power source possibilities include light captured by photovoltaic cells, vibration or pressure captured by a piezoelectric element, temperature differentials captured by a thermo-electric generator, radio energy captured by an antenna and even biochemical energy from living cells by extracting energy from blood sugar.

Equivalent Series (L) Inductance E

Basic electronic or electrical design, theoretically treat components as ideal devices, whereby the physical components are far from being ideal as they are connected to circuits through conductive leads and paths, which contain the parasitic four passive characteristics of: Resistance, Capacitance, Inductance and Memristivity. The balance and net positions of the components and device within a circuit, must consider these elements when improving efficiency, longevity and performance. Industry deals with these inherent differences in circuit analysis by using lumped element models to express each physical component as a combination of an ideal component and a small inductor in series, which is a passive value equal to that present within a non-ideal, physical device.

ESD Protection E

Devices and treatment added to the input and output pins on a semiconductor or device, that protects the internal circuitry from the damaging effects of electrostatic discharge.

Ethernet E

Family of network protocols based on asynchronous frames. The Ethernet framing structure provides a flexible payload container with basic addressing and error detection mechanisms and are known as local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). Introduced in 1980, it became standardised in 1983 as IEEE 802.3 and has replaced token ring, FDDI and ARCNET. Ethernet data transfer rates have been increased from the original 2.94 Mbit/s to the latest 100 Gbit/s.

F

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

F

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

F

Farad F

Farad, F

SI Derived Unit

Capacitance

SI Derived Quantity

kg⁻¹·m⁻²·s⁴·A²

SI Base Expression

One farad of capacitance will store one coulomb of charge when the charging force is one volt. Since the farad is a very large unit, capacitance will more commonly expressed as microfarad (uF) or picofarad (pF) values.

Named after Michael Faraday

Farad F

Farad, F

SI Derived Unit

Capacitance

SI Derived Quantity

kg⁻¹·m⁻²·s⁴·A²

SI Base Expression

One farad of capacitance will store one coulomb of charge when the charging force is one volt. Since the farad is a very large unit, capacitance will more commonly expressed as microfarad (uF) or picofarad (pF) values.

Named after
Michael Faraday

Fault Blanking F

Function that that when chosen, will ignore a fault for a predetermined period, acknowledging the fault condition and muting the alert.

Filter F

Circuit filtration design will allow a specific frequency range to pass whilst rejecting others and performing additional signal processing functions, also utilising the rejected frequencies, to improve quality of signal. Filter designs include passive, active, analogue or digital, high-pass, low-pass, band-pass, band-stop, all-pass, discrete or continuous-over-time, linear or non-linear.

Invented by George Campbell, 1910

Filter F

Circuit filtration design will allow a specific frequency range to pass whilst rejecting others and performing additional signal processing functions, also utilising the rejected frequencies, to improve quality of signal. Filter designs include passive, active, analogue or digital, high-pass, low-pass, band-pass, band-stop, all-pass, discrete or continuous-over-time, linear or non-linear.

Invented by
George Campbell, 1910

Firmware F

Software encoded into a ROM, EPROM, EEPROM can provide initial parameters on a system restart or power outage. The ROM BIOS of computers contain basic functions of a device to provide services to higher-level software, yet firmware of an embedded system may be the only program that will run on the system and provide all of its functions.

Invented by Ascher Opler, 1967

Firmware F

Software encoded into a ROM, EPROM, EEPROM can provide initial parameters on a system restart or power outage. The ROM BIOS of computers contain basic functions of a device to provide services to higher-level software, yet firmware of an embedded system may be the only program that will run on the system and provide all of its functions.

Invented by
Ascher Opler, 1967

Floating F

Signals, inputs and outputs are said to be “floating” if there is no connection to any voltage supply, ground, or ground-referenced signal source.

Flyback Induction F

Voltage spikes, witnessed across inductive loads when the power is removed and the magnetic field collapses is a likely event of flyback induction. The current flowing through the inductor cannot change instantly as it is limited by the time constant of the inductor and to eliminate flyback, diodes are required across an inductive load. Known as a flyback, snubber, freewheeling, suppressor, suppression, clamp or catch diode, the perfect diode selection would include a large peak forward current capacity with low forward voltage drop and a reverse breakdown voltage matched to the power supply of the inductor. Schottky diodes have a low forward voltage drop of 0.2V, and are very responsive to reverse bias. When used with a DC coil, a low-value resistor, placed in series with the diode, will dissipate the coil energy faster.

Footprint F

Physical areas pre-specified and used by a component, include a pad pattern for a PCB layout and include layers of component identification, pin size and body clearance.

Invented by Paul Eisler, 1943

Footprint F

Physical areas pre-specified and used by a component, include a pad pattern for a PCB layout and include layers of component identification, pin size and body clearance.

Invented by
Paul Eisler, 1943

Forward Bias F

Voltage potential applied to a solid-state P-N junction, resulting in current flow when the junction has become saturated.

Forward Converter F

Power-supply switching circuit that transfers energy to a secondary winding of a transformer, when transistor switching is required.

Frequency F

Measured in hertz (Hz), this is the number of cycles, per second for any periodic waveform shape as in sinusoidal, square or triangular.

Frequency Hopping Spread Spectrum F

Transmission technology in which the data signal is modulated by a narrowband carrier signal and changes frequency, hopping between a wide band of frequencies which are specified by an algorithm known to the receiving system.

Frequency Modulation F

Encoding of information in a carrier wave by shifting the carrier’s frequency through a defined set of frequencies, representing digits. This instantaneous variation in frequency of the wave, is in direct contrast with amplitude modulation, which modifies the amplitude of the carrier wave, and maintains a constant frequency.

Invented by Edwin Howard Armstrong, 1933

Frequency Modulation F

Encoding of information in a carrier wave by shifting the carrier’s frequency through a defined set of frequencies, representing digits. This instantaneous variation in frequency of the wave, is in direct contrast with amplitude modulation, which modifies the amplitude of the carrier wave, and maintains a constant frequency.

Invented by
Edwin Howard Armstrong, 1933

G

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

G

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

G

Gain G

Determination of the amount of amplification accomplished by a circuit as in a gain of three means the output is scaled up to three times the amplitude of the input.

Gallium Arsenide G

GaAs, is a semiconductor material used for optoelectronic products such as LEDs, Photo Cells, Avalanche Junctions and for high-speed electronic devices.

Gamma Correction G

Applying function that transform the brightness or luminance values, gamma functions are predominantly nonlinear, are monotonic and designed to affect highlights, mid-tones, and shadows separately. Commonly applied to make light-emitting devices, as in displays, match the brightness curve of the human eye.

Gate Logic G

Logical states created by transistor or relay logic and includes the following gates: AND, NAND, OR, NOR, XOR, XNOR, BUFFER & INVERTER.

Gate AND
This is the result of a logical device that states if two or more inputs equal 1, then give a value of 1, if not, then give a value of 0.

Input A (0) Input B (0) Output (0)
Input A (0) Input B (1) Output (0) Input A (1) Input B (0) Output (0)
Input A (1) Input B (1) Output (1)

Gate NAND
Stands for NOT-AND. Gives an inverted output of AND logic, false inputs returns true.

Input A (0) Input B (0) Output (1)
Input A (0) Input B (1) Output (1) Input A (1) Input B (0) Output (1)
Input A (1) Input B (1) Output (0)

Gate OR
Generates a logic 1 if any one of its two or more inputs are 1.

Input A (0) Input B (0) Output (0)
Input A (0) Input B (1) Output (1) Input A (1) Input B (0) Output (1)
Input A (1) Input B (1) Output (1)

Gate NOR
Stands for NOT-OR. Gives an inverted output of OR logic.

Input A (0) Input B (0) Output (1)
Input A (0) Input B (1) Output (0) Input A (1) Input B (0) Output (0)
Input A (1) Input B (1) Output (0)

Gate XOR
Known as an Exclusive OR gate, it has an output of true, only when exactly one of its inputs are true. If both inputs are false, or if both of its inputs are true, then the output of the gate is false.

Input A (0) Input B (0) Output (0)
Input A (0) Input B (1) Output (1) Input A (1) Input B (0) Output (1)
Input A (1) Input B (1) Output (0)

Gate XNOR
Known as an Exclusive OR gate, it has an output of true, only when exactly one of its inputs are true. If both inputs are false, or if both of its inputs are true, then the output of the gate is false.

Input A (0) Input B (0) Output (1)
Input A (0) Input B (1) Output (0) Input A (1) Input B (0) Output (0)
Input A (1) Input B (1) Output (1)

Gate BUFFER
To isolate logic gates from each other or to drive or switch higher than normal loads, such as relays, solenoids and lamps without the need for inversion. The “Buffer” performs no inversion or decision making capabilities but instead produces an output which exactly matches that of its input.

Input (0) Output (0) Input (1) Output (1)

Gate INVERTER
This gate, also known as a NOT, is a logic gate with one input signal and sends an output, of 1 if it receives an input of 0 or Input of 1 with an output of 0.

Input (0) Output (1) Input (1) Output (0)

Gate Logic G

Logical states created by transistor or relay logic and includes the following gates: AND, NAND, OR, NOR, XOR, XNOR, BUFFER & INVERTER.

Gate AND
This is the result of a logical device that states if two or more inputs equal 1, then give a value of 1, if not, then give a value of 0.

Input A (0) Input B (0) Output (0)
Input A (0) Input B (1) Output (0)
Input A (1) Input B (0) Output (0)
Input A (1) Input B (1) Output (1)

Gate NAND
Stands for NOT-AND. Gives an inverted output of AND logic, false inputs returns true.

Input A (0) Input B (0) Output (1)
Input A (0) Input B (1) Output (1)
Input A (1) Input B (0) Output (1)
Input A (1) Input B (1) Output (0)

Gate OR
Generates a logic 1 if any one of its two or more inputs are 1.

Input A (0) Input B (0) Output (0)
Input A (0) Input B (1) Output (1)
Input A (1) Input B (0) Output (1)
Input A (1) Input B (1) Output (1)

Gate NOR
Stands for NOT-OR. Gives an inverted output of OR logic.

Input A (0) Input B (0) Output (1)
Input A (0) Input B (1) Output (0)
Input A (1) Input B (0) Output (0)
Input A (1) Input B (1) Output (0)

Gate XOR
Known as an Exclusive OR gate, it has an output of true, only when exactly one of its inputs are true. If both inputs are false, or if both of its inputs are true, then the output of the gate is false.

Input A (0) Input B (0) Output (0)
Input A (0) Input B (1) Output (1)
Input A (1) Input B (0) Output (1)
Input A (1) Input B (1) Output (0)

Gate XNOR
Known as an Exclusive OR gate, it has an output of true, only when exactly one of its inputs are true. If both inputs are false, or if both of its inputs are true, then the output of the gate is false.

Input A (0) Input B (0) Output (1)
Input A (0) Input B (1) Output (0)
Input A (1) Input B (0) Output (0)
Input A (1) Input B (1) Output (1)

Gate BUFFER
To isolate logic gates from each other or to drive or switch higher than normal loads, such as relays, solenoids and lamps without the need for inversion. The “Buffer” performs no inversion or decision making capabilities but instead produces an output which exactly matches that of its input.

Input (0) Output (0)
Input (1) Output (1)

Gate INVERTER
This gate, also known as a NOT, is a logic gate with one input signal and sends an output, of 1 if it receives an input of 0 or Input of 1 with an output of 0.

Input (0) Output (1)
Input (1) Output (0)

Gaussian Frequency Shift Keying G

A type of FSK modulation which uses a Gaussian filter to shape the pulses before they are modulated. This reduces the spectral bandwidth and out-of-band spectrum, to meet adjacent-channel power rejection requirements. Bluetooth uses GFSK.

Gerber File G

Named after Gerber Scientific Corp., the original vector plotter manufacturer, this term is used to signify a set of data files that define the top, bottom, inner layers, silkscreen, solder masks and a drill list, used to make a printed circuit board.

Invented by Joseph Gerber, 1980

Gerber File G

Named after Gerber Scientific Corp., the original vector plotter manufacturer, this term is used to signify a set of data files that define the top, bottom, inner layers, silkscreen, solder masks and a drill list, used to make a printed circuit board.

Invented by
Joseph Gerber, 1980

Gray G

Gray, Gy

SI Derived Unit

Absorbed Dose, Specific Energy (Imparted), Kerma

SI Derived Quantity

m²·s⁻²

SI Base Expression

This unit is defined as the absorption of one joule of radiation energy per one kilogram of matter. It is used as a measure of absorbed dose, specific energy (imparted), and kerma (an acronym for “kinetic energy released per unit mass”). It is a physical quantity, and does not take into account any biological context. Unlike the pre-1971 non-SI roentgen unit of radiation exposure, the Gray when used for absorbed dose is defined independently of any target material. When measuring kerma the reference target material must be defined explicitly, usually as dry air at standard temperature and pressure.

Named after Louis Harold Gray

Gray G

Gray, Gy

SI Derived Unit

Absorbed Dose, Specific Energy (Imparted), Kerma

SI Derived Quantity

m²·s⁻²

SI Base Expression

This unit is defined as the absorption of one joule of radiation energy per one kilogram of matter. It is used as a measure of absorbed dose, specific energy (imparted), and kerma (an acronym for “kinetic energy released per unit mass”). It is a physical quantity, and does not take into account any biological context. Unlike the pre-1971 non-SI roentgen unit of radiation exposure, the Gray when used for absorbed dose is defined independently of any target material. When measuring kerma the reference target material must be defined explicitly, usually as dry air at standard temperature and pressure.

Named after
Louis Harold Gray

Ground G

Common return path for current in an electrical circuit which serves as a reference point for measuring all other potentials in a circuit. Generally assumed to be at zero potential with respect to the earth. Other than earth references may be used such as the chassis of an automobile (chassis ground) or some arbitrary point in a circuit (circuit ground) like the negative side of the power source.

H

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

H

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

H

H Bridge H

Circuit diagram which resembles the letter “H” with the load as the horizontal line, connected between two pairs of intersecting lines. Very common in DC motor-drive applications where switches are used in the “vertical” branches of the “H” to control the direction of current flow, and thus the rotational direction of the motor.

Highway Addressable Remote Transducer H

Communication mode used for the transmission of digital signals that are superimposed on the analogue signal of a 4–20mA current loop. The HART protocol is based on the phase continuous frequency shift keying (FSK) technique with Bit 0, modulated to a 2,200Hz sinusoidal signal, and bit 1 is modulated to a 1,200Hz sinusoidal signal with a baud rate of 1,200bps. These two frequencies can easily be superimposed on the analogue current-loop signal, which is in the range of DC to 10Hz, without affecting either signal and the unique nature of this protocol enables simultaneous analogue and digital communication on the same wire.

Henry H

Henry, H

SI Derived Unit

Inductance

SI Derived Quantity

kg · m² · s⁻² · A⁻²

SI Base Expression

This is the unit of inductance in which an induced electromotive force of one volt is produced when the current is varied at the rate of one ampere per second.

Named after Joseph Henry

Henry H

Henry, H

SI Derived Unit

Inductance

SI Derived Quantity

kg · m² · s⁻² · A⁻²

SI Base Expression

This is the unit of inductance in which an induced electromotive force of one volt is produced when the current is varied at the rate of one ampere per second.

Named after
Joseph Henry

Hertz H

Hertz, Hz

SI Derived Unit

Frequency

SI Derived Quantity

s^-1

SI Base Expression

This unit of frequency is equal to cycles per second. In defining the second, “the standard to be employed is the transition between the hyperfine levels F = 4, M = 0 and F = 3, M = 0 of the ground state 2S_1/2 of the caesium 133 atom, unperturbed by external fields, and that the frequency of this transition is assigned the value 9,192,631,770 hertz”, effectively defining the hertz and the second simultaneously.

Named after Heinrich Hertz

Hertz H

Hertz, Hz

SI Derived Unit

Frequency

SI Derived Quantity

s^-1

SI Base Expression

This unit of frequency is equal to cycles per second. In defining the second, “the standard to be employed is the transition between the hyperfine levels F = 4, M = 0 and F = 3, M = 0 of the ground state 2S_1/2 of the caesium 133 atom, unperturbed by external fields, and that the frequency of this transition is assigned the value 9,192,631,770 hertz”, effectively defining the hertz and the second simultaneously.

Named after
Heinrich Hertz

Hyper Text Markup Language H

Standard language used to create web pages and with CSS and JavaScript, HTML is a key technology, used to create websites, web applications. The HTML elements form the building blocks of all websites as it allows for images and objects to be embedded and used to create interactive forms, create structured documents by denoting the structural architecture of text such as headings, paragraphs, lists, links and quotes. Embedding scripts written languages as in JavaScript will affect the behaviour of HTML web pages as web browsers can refer to Cascading Style Sheets (CSS) to define the look and layout of text and other material.

Hyper Text Transport Protocol H

Structured text, using logical links (hyperlinks) between nodes containing text, HTTP is the protocol to exchange or transfer hypertext.

I

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Institute of Electrical and Electronics Engineers I

Organisation and sponsor of many electrical and electronic standards and are a technical professional association throughout 175 countries.

Intermediate Frequency I

Radio communications systems modulate a carrier frequency with a baseband signal in order to achieve radio transmission. In many cases, carriers are not modulated directly and instead, a lower IF signal is modulated and processed, then at a later circuit stage, the IF signal will be converted up to the transmission frequency band.

Image Frequency I

Receivers typically convert RF signals to a lower Intermediate Frequency (IF) for demodulation. In addition to the IF, a second signal, called the “image frequency” is often generated and filtered out.

Impedance I

Z, is a measure of the opposition to electrical flow and is measured in ohms. For DC systems, impedance and resistance are the same, defined as the voltage across an element divided by the current (R = V/I). In AC systems, the “reactance” enters the equation due to the frequency-dependent contributions of capacitance and inductance. Impedance in an AC system is still measured in ohms and represented by the equation Z = V/I, but V and I are frequency-dependent.

Discovered by Oliver Heaviside, 1886

Impedance I

Z, is a measure of the opposition to electrical flow and is measured in ohms. For DC systems, impedance and resistance are the same, defined as the voltage across an element divided by the current (R = V/I). In AC systems, the “reactance” enters the equation due to the frequency-dependent contributions of capacitance and inductance. Impedance in an AC system is still measured in ohms and represented by the equation Z = V/I, but V and I are frequency-dependent.

Discovered by
Oliver Heaviside, 1886

Image Rejection I

Measure of the ability of a receiver to reject signals at its image frequency. Expressed as a ratio, in dB, the sensitivity of a receiver, at the desired frequency, versus the sensitivity at the image frequency.

Inductance I

L, is the property of an electrical conductor in which a change in electrical current, induces an electromotive force in both the conductor and any nearby conductors by mutual inductance.

A steady current creates a steady magnetic field as described by the Oersted Law and a time-varying magnetic field induces an electromotive force in nearby conductors, as described by the Faraday Law of Induction and according to Lenz Law, a changing electric current through a circuit that contains inductance, induces a proportional voltage, which opposes the change in current, self-inductance. The term inductance was named by Oliver Heaviside in 1886 and the use of the symbol L for inductance, is in honour of physicist Heinrich Lenz.

The International Units of SI, has the measurement unit for inductance as the henry, with the unit symbol H, in honour of Joseph Henry, who discovered inductance independently of, but not before, Michael Faraday.

Discovered by Michael Faraday, 1831

Inductance I

L, is the property of an electrical conductor in which a change in electrical current, induces an electromotive force in both the conductor and any nearby conductors by mutual inductance.

A steady current creates a steady magnetic field as described by the Oersted Law and a time-varying magnetic field induces an electromotive force in nearby conductors, as described by the Faraday Law of Induction and according to Lenz Law, a changing electric current through a circuit that contains inductance, induces a proportional voltage, which opposes the change in current, self-inductance. The term inductance was named by Oliver Heaviside in 1886 and the use of the symbol L for inductance, is in honour of physicist Heinrich Lenz.

The International Units of SI, has the measurement unit for inductance as the henry, with the unit symbol H, in honour of Joseph Henry, who discovered inductance independently of, but not before, Michael Faraday.

Discovered by
Michael Faraday, 1831

Inductive Reactance I

X_L, is due to electric currents produce magnetic fields which change as a result of the back and forth current oscillations. This difference in the magnetic field induces another electric current to flow in the same wire and in opposition to the original current flow, resulting in the inductive reactance being in opposition to the change of current through an element. This effect results in a delay, or a phase shift, of the alternating current with respect to alternating voltage. As a reference, an ideal inductor (with no resistance) will cause the current to lag the voltage by a quarter cycle, or 90°.

X_L = ωL = 2 π ƒ L

Inductive reactance X_L (Ω for Ohms) is proportional to the sinusoidal signal frequency ƒ (Hz for Hertz) and the inductance L (H for Henry).

Discovered by George Ashley Campbell, 1899

Inductive Reactance I

X_L, is due to electric currents produce magnetic fields which change as a result of the back and forth current oscillations. This difference in the magnetic field induces another electric current to flow in the same wire and in opposition to the original current flow, resulting in the inductive reactance being in opposition to the change of current through an element. This effect results in a delay, or a phase shift, of the alternating current with respect to alternating voltage. As a reference, an ideal inductor (with no resistance) will cause the current to lag the voltage by a quarter cycle, or 90°.

X_L = ωL = 2 π ƒ L

Inductive reactance X_L (Ω for Ohms) is proportional to the sinusoidal signal frequency ƒ (Hz for Hertz) and the inductance L (H for Henry).

Discovered by
George Ashley Campbell, 1899

Infrared Radiation I

Light spectrum of 700 nanometres, 430 THz to 1 mm, 300 GHz. Falling below the visible light spectrum, infrared has a lower frequency and longer wavelength than visible light, with part of this spectrum radiated as heat. Infrared capabilities are used by thermal-imaging cameras to examine temperature limits in insulation and electrical systems, night-vision devices, photography and astronomy, imaging and identifying highly red-shifted objects of the early universe.

Discovered by Sir Frederick William Herschel, 1800

Infrared Radiation I

Light spectrum of 700 nanometres, 430 THz to 1 mm, 300 GHz. Falling below the visible light spectrum, infrared has a lower frequency and longer wavelength than visible light, with part of this spectrum radiated as heat. Infrared capabilities are used by thermal-imaging cameras to examine temperature limits in insulation and electrical systems, night-vision devices, photography and astronomy, imaging and identifying highly red-shifted objects of the early universe.

Discovered by
Sir Frederick William Herschel, 1800

InterModulation Distortion I

Signal errors of a type that manifests when two signals mix in non-linear circuits or devices resulting in new frequency components being created, that are not in the original signal.

J

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J

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Joint Photography Experts Group J

Method of digital image compression, with an adjustable compression ratio between storage size and image quality. Maximum image size of 65,535 × 65,535 pixels = 4,294,836,225 pixels.

Joule J

Joule, J

SI Derived Unit

Energy, Work, Amount of Heat

SI Derived Quantity

kg·m²·s⁻²

SI Base Expression

This is the basic unit of electrical, mechanical, and thermal energy. As a unit of electrical energy it is equal to the energy carried by 1 coulomb of charge being propelled by an electromotive force of 1 volt.

Named after Joseph Henry

Joule J

Joule, J

SI Derived Unit

Energy, Work, Amount of Heat

SI Derived Quantity

kg·m²·s⁻²

SI Base Expression

This is the basic unit of electrical, mechanical, and thermal energy. As a unit of electrical energy it is equal to the energy carried by 1 coulomb of charge being propelled by an electromotive force of 1 volt.

Named after
Joseph Henry

K

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Katal K

Katal, kat

SI Derived Unit

Catalytic Activity

SI Derived Quantity

mol · s^-1

SI Base Expression

This is a unit for quantifying the catalytic activity of enzymes (measuring the enzymatic activity level in enzyme catalysis) and other catalysts. The katal is not used to express the rate of a reaction; that is expressed in units of concentration per second (or moles per litre per second). It is used to express catalytic activity which is a property of the catalyst.

Kelvin K

Kelvin, K

SI Base Unit

Temperature, Θ

SI Base Quantity

The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all thermal motion ceases in the classical description of thermodynamics. The kelvin is defined as the fraction 1⁄273.16 of the thermodynamic temperature of the triple point of water (exactly 0.01 °C or 32.018 °F). The triple point of water is exactly 273.16 K.

Formally, as defined in 2014:
“The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.”

Proposed:
“The kelvin, K, is the unit of thermodynamic temperature; its magnitude is set by fixing the numerical value of the Boltzmann constant to be equal to exactly 1.380 65X × 10⁻²³ when it is expressed in the unit s⁻²·m²·kg·K⁻¹, which is equal to J·K⁻¹.”

Discovered by Lord William Kelvin, 1848

Kelvin K

Kelvin, K

SI Base Unit

Temperature, Θ

SI Base Quantity

The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all thermal motion ceases in the classical description of thermodynamics. The kelvin is defined as the fraction 1⁄273.16 of the thermodynamic temperature of the triple point of water (exactly 0.01 °C or 32.018 °F). The triple point of water is exactly 273.16 K.

Formally, as defined in 2014:
“The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.”

Proposed:
“The kelvin, K, is the unit of thermodynamic temperature; its magnitude is set by fixing the numerical value of the Boltzmann constant to be equal to exactly 1.380 65X × 10⁻²³ when it is expressed in the unit s⁻²·m²·kg·K⁻¹, which is equal to J·K⁻¹.”

Discovered by
Lord William Kelvin, 1848

Kilogram K

Kilogram, kg

SI Base Unit

Mass, M

SI Base Quantity

The gram, 1/1000th of a kilogram, was originally defined as the mass of one cubic centimetre of water at the melting point of water. The original prototype kilogram, manufactured in 1799, has a mass equal to the mass of 1.000’028 dm³ of water at its maximum density at approximately 4 °C. The kilogram is the only SI base unit with a prefix (kilo) as part of its name and directly defined by an artefact rather than a fundamental physical property. Three SI Base units (Cd, A, mol) and 17 SI Derived units (N, Pa, J, W, C, V, F, Ω, S, Wb, T, H, kat, Gy, Sv, lm, lx) are defined relative to the kilogram. Only 8 SI units do not require the kilogram in their definition: temperature (K, °C), time and frequency (s, Hz, Bq), length (m), and angle (rad, sr). The International Committee for Weights and Measures have undertaken to redefine the kilogram in terms of a fundamental constant of nature, as in the Planck constant.

Formally, as defined in 2014:
“The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram.”

Proposed:
“The kilogram, kg, is the unit of mass; its magnitude is set by fixing the numerical value of the Planck constant to be equal to exactly 6.626 06X × 10⁻³⁴ when it is expressed in the unit s⁻¹·m²·kg, which is equal to J·s.”

L

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Latency L

Known as propagation delay, this is the difference in time interval between input and output events.

Linear L

Circuit or component where the output is a straight line (direct proportion) function of the input. E.g.: VOUT = k*VI, where k is a constant.

Linear Feedback Shift Register L

Shift register in which some of its outputs are connected to the input through logic gates (typically, an Exclusive-Or (XOR) gate.

Lumen L

Lumen, lm

SI Derived Unit

Luminous Flux

SI Derived Quantity

cd · sr

SI Base Expression

This is a measure of the total “amount” of visible light emitted by a source. Luminous flux differs from power (Radiant Flux) in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light. Radiant flux measurements indicate the total power of all electromagnetic waves emitted, independent of the eye’s ability to perceive it. Lumens are related to lux in that one lux is one lumen per square meter.

Lux L

Lux, lx

SI Derived Unit

Illuminance

SI Derived Quantity

cd · sr · m⁻²

SI Base Expression

This is a measure of how much luminous flux (lumens) is spread over a given area. One lux is equal to one lumen per square metre.

M

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Make-Before-Break M

Operation of switches or relays that are designed to maintain contact before opening the connection, ensuring a non-interrupted conductive path.

Mask M

Chemical and heat-resistant silkscreen material applied to a copper clad fibre glass board which prevents etching, plating, or soldering in specific areas on the prospective printed circuit board.

Media Access Control Address M

Hardware address, registered within an PROM and resident within the MAC layer, interfaces directly with the network to uniquely identify each node of an Ethernet network.

Metre M

Metre, m

SI Base Unit

Length, L

SI Base Quantity

Originally defined as one ten-millionth of the distance from the equator to the North Pole. In 1889, it was redefined in terms of a prototype metre bar then in 1960, the metre was redefined as equal to 1 650 763.73 wavelengths of the orange-red emission line in the electromagnetic spectrum of the krypton-86 atom in a vacuum. The metre is now defined as the path length travelled by light in a given time with practical laboratory length measurements, in metres, determined by counting the number of wavelengths of laser light and converting the selected unit of wavelength to metres. Three major factors limit this accuracy for length measurement: Uncertainty in vacuum wavelength of the source, refractive index of the medium and count resolution of the interferometer.

Formally, as defined in 2014:
“The metre is the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 of a second.”

Proposed:
“The metre, m, is the unit of length; its magnitude is set by fixing the numerical value of the speed of light in vacuum to be equal to exactly 299,792,458 when it is expressed in the unit m·s⁻¹.”

Micro Electronic Mechanical Systems M

Microelectromechanical systems combine mechanical and electrical components, fabricated with semiconductor fabrication techniques. Common examples include switches, valves, waveguides, pressure and acceleration sensors and combined sensor, amplification and conditioning circuitry.

Multiple Input, Multiple Output M

System with multiple antennae and multiple radios, taking advantage of multipath effects, where a transmitted signal arrives at the receiver through a number of different paths. Each path can have a different time delay, and the result is that multiple instances of a single transmitted symbol arrive at the receiver at different times.

MIMO systems use data arriving at the receiver at different times through different paths to improve the quality and speed of the data link, rather than relying on a single antenna path to receive an entire message.

Mole M

Mole, mol

SI Base Unit

Amount of Substance, N

SI Base Quantity

The mass per mole of a substance is called its molar mass and is measured in grams per mole, exactly equal to its mean molecular or atomic mass, that is measured in unified atomic mass units. The number of elementary entities in a sample of a substance is technically called its (chemical) amount, the unit for that physical quantity, the mole and can be determined by dividing the mass of the sample by the molar mass of the substance.

Formally, as defined in 2014:
“The mole is the amount of substance of a system that contains as many elementary entities as there are atoms in 0.012 kilogram of carbon-12. When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.”

Proposed:
“The mole, mol, is the unit of amount of substance of a specified elementary entity, which may be an atom, molecule, ion, electron, any other particle or a specified group of such particles; its magnitude is set by fixing the numerical value of the Avogadro constant to be equal to exactly 6.022 14X × 10²³ when it is expressed in the unit mol⁻¹.”

N

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N

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National Television Standards Committee N

Colour television standards were established by this committee in 1953 and was built on the specifications outlined in the 1941 Black and White Television Standard. Dependency on accurate phase control made it difficult to calibrate an accurate colour reference for transmission and reception and amended the NTSC standard to add a colour subcarrier, modulated by two colour-differential signals, adding to the luminance signal with a subcarrier reference of 3.579545 MHz.

Newton N

Newton, N

SI Derived Unit

Force

SI Derived Quantity

kg · m · s⁻²

SI Base Expression

Force (F) is any interaction when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity, which includes to begin moving from a state of rest, as in to accelerate. Weight (W) of an object is the force on the object due to gravity. Weight is the product of the mass (m) of the object and the magnitude of the local gravitational acceleration (g), thus: W = mg.

Named after Sir Isaac Newton

Newton N

Newton, N

SI Derived Unit

Force

SI Derived Quantity

kg · m · s⁻²

SI Base Expression

Force (F) is any interaction when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity, which includes to begin moving from a state of rest, as in to accelerate. Weight (W) of an object is the force on the object due to gravity. Weight is the product of the mass (m) of the object and the magnitude of the local gravitational acceleration (g), thus: W = mg.

Named after
Sir Isaac Newton

Newton’s Laws of Motion N

… with Newton’s First Law of Motion: A body continues in its state of constant velocity (which may be zero) unless it is acted upon by an external force.

… with Newton’s Second Law of Motion: For an unbalanced force acting on a body, the acceleration produced is proportional to the force impressed; the constant of proportionality is the inertial mass of the body.

… with Newton’s Third Law of Motion: In a system where no external forces are present, every action force is always opposed by an equal and opposite reaction.

Named after Sir Isaac Newton

Newton’s Laws of Motion N

… with Newton’s First Law of Motion: A body continues in its state of constant velocity (which may be zero) unless it is acted upon by an external force.

… with Newton’s Second Law of Motion: For an unbalanced force acting on a body, the acceleration produced is proportional to the force impressed; the constant of proportionality is the inertial mass of the body.

… with Newton’s Third Law of Motion: In a system where no external forces are present, every action force is always opposed by an equal and opposite reaction.

Named after
Sir Isaac Newton

Non Return to Zero N

Binary encoding scheme in which ones and zeroes are represented by opposite and alternating high and low voltages and where there is no return to a zero reference voltage between the encoded bits of two values, low and high.

Nonlinear N

System which does not satisfy the superposition principle, meaning an output of a nonlinear system is not directly proportional to the input. Most systems are inherently nonlinear in nature with behaviour of a nonlinear system appearing to be chaotic, unpredictable or counterintuitive, yet such behaviour is absolutely not random.

Norton Theorem N

Method for reducing complex networks of bilateral components to one current source and applying one shunt of resistance across the load terminals. Any linear electrical network with voltage and current sources and only resistances can be replaced at terminals A-B by an equivalent current source I_NO in parallel connection with an equivalent resistance R_NO.

This equivalent current I_NO is the current obtained at terminals A-B of the network with terminals A-B short circuited. This equivalent resistance R_NO is the resistance obtained at terminals A-B of the network with all its voltage sources short circuited and all its current sources open circuited. For AC systems the theorem can be applied to reactive impedances as well as resistances.

Discovered by Edward Lawry Norton, 1926

Norton Theorem N

Method for reducing complex networks of bilateral components to one current source and applying one shunt of resistance across the load terminals. Any linear electrical network with voltage and current sources and only resistances can be replaced at terminals A-B by an equivalent current source I_NO in parallel connection with an equivalent resistance R_NO.

This equivalent current I_NO is the current obtained at terminals A-B of the network with terminals A-B short circuited. This equivalent resistance R_NO is the resistance obtained at terminals A-B of the network with all its voltage sources short circuited and all its current sources open circuited. For AC systems the theorem can be applied to reactive impedances as well as resistances.

Discovered by
Edward Lawry Norton, 1926

O

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O

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Ohm O

Ohm, Ω

SI Derived Unit

Electric Resistance

SI Derived Quantity

kg · m² · s⁻³ · A⁻²

SI Base Expression

The ohm is defined as an electrical resistance between two points of a conductor when a constant potential difference of 1 volt, applied to these points, produces in the conductor a current of 1 ampere, the conductor not being the seat of any electromotive force. In alternating current circuits, electrical impedance is also measured in ohms (Ω).

Named after Georg Simon Ohm

Ohm O

Ohm, Ω

SI Derived Unit

Electric Resistance

SI Derived Quantity

kg · m² · s⁻³ · A⁻²

SI Base Expression

The ohm is defined as an electrical resistance between two points of a conductor when a constant potential difference of 1 volt, applied to these points, produces in the conductor a current of 1 ampere, the conductor not being the seat of any electromotive force. In alternating current circuits, electrical impedance is also measured in ohms (Ω).

Named after
Georg Simon Ohm

Operational Amplifier O

Ideal operational amplifiers have infinite input impedance, infinite open-loop gain, zero output impedance, infinite bandwidth, and zero noise. It has positive and negative inputs which allow circuits that use feedback to achieve a wide range of functions. Using op amps, it is easy to make amplifiers, comparators, log amps, filters, oscillators, data converters, level translators and references.

Mathematical functions and integration can be easily accomplished and are the building block for analogue design, with one key design being nodal analysis. Since the input impedance is infinite, the current and input nodes define the behaviour of the circuit.

Orthogonal Frequency Division Multiplexing O

Method for multiplexing signals which divides the available bandwidth into a series of frequencies known as tones and utilising a 5GHz channel, divides each into 400 discrete tones at different frequencies. Orthogonal tones do not interfere with each other when the peak of one tone corresponds with the null. All frequencies fade but the rapid switching, frequency-hopping technique is intended to allow more robust data service.

Oscillator O

Circuit that converts dc power into ac signals with constant frequency and also known as a signal generator, an instrument for generating AC signals, with variable frequency and amplitude.

P

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Pascal P

Pascal, Pa

SI Derived Unit

Pressure, Stress

SI Derived Quantity

kg · m^-1 · s⁻²

SI Base Expression

The pascal (Pa), is one newton per square metre. Pressure (P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure. Multiple units of the pascal are the hectopascal (1 hPa ≡ 100 Pa) which is equal to 1 mbar, the kilopascal (1 kPa ≡ 1,000 Pa), the megapascal (1 MPa ≡ 1,000,000 Pa), and the gigapascal (1 GPa ≡ 1,000,000,000 Pa). The unit of measurement called the standard atmosphere (atm) is defined as 101.325 kPa and approximates to the average pressure at sea-level at 45° N.

Named after Blaise Pascal

Pascal P

Pascal, Pa

SI Derived Unit

Pressure, Stress

SI Derived Quantity

kg · m^-1 · s⁻²

SI Base Expression

The pascal (Pa), is one newton per square metre. Pressure (P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure. Multiple units of the pascal are the hectopascal (1 hPa ≡ 100 Pa) which is equal to 1 mbar, the kilopascal (1 kPa ≡ 1,000 Pa), the megapascal (1 MPa ≡ 1,000,000 Pa), and the gigapascal (1 GPa ≡ 1,000,000,000 Pa). The unit of measurement called the standard atmosphere (atm) is defined as 101.325 kPa and approximates to the average pressure at sea-level at 45° N.

Named after
Blaise Pascal

Phase Alternate Line P

Television standard used throughout Europe that is similar to NTSC, but uses subcarrier phase alternation to reduce the sensitivity to phase errors that would be displayed as colour errors and is commonly used with 626-line, 50 Hz scanning systems, with a subcarrier frequency of 4.43362 MHz.

Phase-Locked Loop P

Control system that generates a signal that has a fixed relation to the phase of a “reference” signal. A phase-locked loop circuit responds to both the frequency and the phase of the input signals, automatically raising or lowering the frequency of a controlled oscillator until it is matched to the reference in both frequency and phase. Phase-locked loops are widely used in radio, telecommunications, computers and other electronic applications. They may generate stable frequencies, recover a signal from a noisy communication channel, or distribute clock timing pulses in digital logic designs such as microprocessors.

Plesiochronous Digital Hierarchy P

Time-division multiplexed network used by telecommunications companies to transport phone calls and data over copper cabling with the entire network sharing a common frequency throughout its structure.

Positive Temperature Coefficient P

Resistance of a component rises with temperature and has a positive temperature coefficient that can be used to provide as an element in the feedback circuit to maintain constant output amplitude regardless of frequency.

Power Factor P

PF, AC circuits have a power factor that is the ratio of the real power that is used to do work and the apparent power that is supplied to the circuit and are expressed as a value of between 0 and 1, with 0 being an inductive load with Reactive Power with no Real Power and 1 being a resistive load with Real Power with no Reactive Power. The power factor is equal to the real or true power, P in watts (W) divided by the apparent power S in volt-ampere (VA):

PF = P_(W) / S_(VA)

P = Real Power in Watts, W & S = Apparent Power, Volt·Amps (VA).

Pre-Bias Soft Start P

Power Supply feature that prevents discharging of the output capacitor when the power supply starts up preventing oscillator problems will a cold start or large voltage disturbances on the output voltage bus.

Pressure Cooker Test P

Testing of components under high temperature, humidity, and pressure conditions. Also called an Autoclave or Pressure Pot Test.

Printed Circuit Board P

Fiberglass board with copper foil to be etched, leaving a conductive track for conductors to interconnect, attaching electronic components. Non-conductive material, generally made of fibreglass and is clad with copper that will have a resistive coating deposited as an image, which will create conductive lines as tracks, then etched in an acid.

Copper coatings are applied in the form of a screen-print and tinned pads for the through-hole components and pads devoid of holes for the surface mount components. Printed circuit boards are made with single or multiple layers as a sandwich of many conductive layers.

Programmable Logic Controller P

Microprocessor-based system that provides factory and plant automation by monitoring sensors and controlling actuators in real time.

Propagation Delay P

Logic device process delay value as to the amount of time between when the input is stable and valid to when the output is stable and valid.

Pulse-Code Modulation P

Conversion of analogue signals into digital, binary (0 or 1), coded pulses, decreasing noise susceptibility. PAM, PFM and PWM are examples of PCM methods.

Pulse-Frequency Modulation P

Pulse modulation technique, of frequency varied with the input signal amplitude. The duty cycle of the modulated signal does not change as it remains a square wave with changing frequency, PFM is also referred to as square-wave FM.

Pulse Width Modulation P

Method for using pulse width to encode or modulate a signal by varying the pulse width and edge of the waveform.

Q

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Q Factor Q

Measure of the quality of a resonant (tank) circuit. A High-Q circuit has mostly reactive components with low resistance. It resonates strongly, with low loss and has a low bandwidth relative to its centre frequency.

Quadrature Q

The relation between two waves of the same frequency, but one-quarter of a cycle (90°) out of phase.

Quadrature Amplitude Modulation Q

Modulation method in which two signals are used to modulate two carriers in quadrature (90 degrees out of phase with each other). Common applications are PAL and NTSC colour television transmission and modems to increase data bandwidth.

Quadrature Phase Shift Keying Q

Form of Phase Shift Keying in which two bits are modulated at once, selecting one of four possible carrier phase shifts (0, 90, 180, or 270 degrees) and allows the signal to carry twice as much information as ordinary PSK using the same bandwidth. Used for satellite transmission of video, modems, videoconferencing and cellular phone systems.

Quiescent Q

Electronic circuit have a quiet state in which the circuit is driving no load and its inputs are not cycling. Most commonly used for specifying the “quiescent current” which is the current consumed by a circuit when it in a quiescent state.

R

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R 2 R Ladder R

Method for D/A conversion which employs a ladder-shaped resistor array composed of two resistor values: R and 2R. Each bit in the digital input switches a ladder’s rungs in and out of the network to change the output voltage by an amount proportional to the significance of the bit.

Radian R

Radian, rad

SI Derived Unit

Plane Angle

SI Derived Quantity

m/m

SI Base Expression

An angle’s measurement in radians is numerically equal to the length of a corresponding arc of a unit circle; one radian is just under 57.3 degrees (when the arc length is equal to the radius). One radian is equal to 180/π degrees. To convert from radians to degrees, multiply by 180/π.

Named after Roger Cotes

Radian R

Radian, rad

SI Derived Unit

Plane Angle

SI Derived Quantity

m/m

SI Base Expression

An angle’s measurement in radians is numerically equal to the length of a corresponding arc of a unit circle; one radian is just under 57.3 degrees (when the arc length is equal to the radius). One radian is equal to 180/π degrees. To convert from radians to degrees, multiply by 180/π.

Named after
Roger Cotes

Radio Frequency IDentification R

Unique identification of an object using a tag or module carrying a unique ID number as a code that is made using an RF connection with no line-of-sight needed.

The tags contain electronically stored information that is powered by electromagnetic induction from magnetic fields produced near the reader, yet others collect energy from the interrogating radio waves and act as a passive transponder and unlike a barcode, they do not need to be within the line of sight of the reader.

Radio Frequency Interference R

Signal noise, echo and harmonics that are unwanted and may originate from RF sources from circuits, devices or sources of electrical generation and static electricity that conflict with radio frequency signals.

Reduced Instruction Set Computer R

Computer hardware designed to support a short list of simple instructions, making hardware simpler and faster, since it does not need to accommodate complex instructions. RISC architecture can be faster, depending on the instruction mix, the design of the instruction set, and how effective the compilers and support software are in translating operations into optimised instructions.

Redundant Array of Independent Disks R

Method of enhancing storage to enable multiple copies of the same data in different places on multiple hard disks to achieve speed and/or data redundancy.

Resistance Capacitance R

Network composed of resistors and capacitors in a series-parallel combination for signal filtration or to delay a signal.

Resistance Temperature Detector R

Device with a significant temperature coefficient (resistance varies with temperature). It is used as a temperature measurement device, usually by passing a low-level current through it and measuring the voltage drop, thermistors are a common type of RTD.

Resonance R

Circuit condition when the inductive reactance (X_L) equals the capacitive reactance (X_C). A resonant circuit is one that has been tuned to that condition and resonant frequency is that frequency that resonance occurs in a circuit and provides a maximum output for one of its circuit variables.

Reverse Recovery Time R

Switching from the conducting to the blocking state, a diode or rectifier has stored charge that must first be discharged, before the diode blocks reverse current. Discharge will take a finite amount of time known as Reverse Recovery and during this time, the diode current may flow in the reverse direction.

Rivest, Shamir and Adleman, Cryptographic Algorithm R

Most popular and commonly used public key cryptographic algorithm in the world was created in 1977 and was named after Rivest, Shamir and Adleman, whom whilst creating an algorithm based on a one-way function, that was to include 4 stages: key generation, key distribution, encryption and decryption. The public key, known to everyone, was to be used to encrypt a message. The encrypted message, with the aid of the public and private key could decrypt the message. The concept, using 3 very large positive integers with modular exponentiation for all m: (m^e)^d mod n=m.

With the difficulty of factoring large integers which are the product of two large prime numbers, not by the multiplication but by establishing what factoring was used as part of the calculations would take an eternity.

The complexity of the system lies in the key generation, as 2 large prime numbers, p and q are generated using the Rabin-Miller primality test algorithm. The modulus n is calculated by multiplying p and q and used by both the public and private keys, providing a link between them with this resulting key length as expressed in bits. The public key consists of the modulus n, the public exponent, e, (normally set at 65537, another prime).

The private key consisting of the modulus n and the private exponent d, is calculated using the Extended Euclidean algorithm to find the multiplicative inverse with respect to the totient of n.

With RSA cryptography, both public and the private keys can encrypt a message and the opposite key from the one used to encrypt a message is used to decrypt it, which is the reason why the RSA algorithm became the most widely used asymmetric algorithm in the world, used for electronic communications, data storage and set the bar for those who followed which also use digital signatures, SSH, OpenPGP, S/MIME, and SSL/TLS.

Invented by Rivest
Adi Shamir & Leonard Adleman, 1977

Root Mean Square R

Value of an alternating current sine wave that is an indication of its equivalence for a direct current value which is effectively equivalent to 70.7% of the maximum (peak) value for this waveform.

Row-Address-Strobe R

Signal notifying DRAM is a data bit that is stored in a cell located by the intersection of a column and row address.

RS-232 R

Serial communication device that allows asynchronous data communication for distances up to 100 metres at speeds up to 20k Baud and characterised by a single-ended, not-differential physical layer with one signal wire for transmission, another for reception, common ground and timing and control signals.

RS-422 R

Serial communication device that allows one transmitter and up to 10 receivers with data transmission rates up to 10 Megabits per second for distances up to 10 metres and up to 100 Kilobits per second for distances up to 1,200 metres). 2 twisted pair of wires are used to carry each signal. The TXD pair and RXD pair are used to carry the data whilst the RTS pair and CTS pair lines are used for handshaking.

RS-485 R

Serial communication device that allows for 32 driver/receivers pairs on a party line data bus, allowing for one to transmit data at any time, whilst the rest simultaneously listen to the data. Two twisted pairs form a full duplex system with handshaking performed by a software protocol.

S

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

S

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

S

S Parameters S

Reflection and transmission coefficients used in impedance matching between high-speed (RF) devices and transmission traces.

Scan Design S

Technique in which the internal registers or flip-flops of a circuit can be chained, to allow an external circuit to easily read and write their contents.
When internal memory elements are not directly accessible from the circuit’s outside pins, testing is difficult because their state is unknown.
With scan design, a signal reconfigures the elements into a “scan chain” and their contents can be read or altered.

Second S

Second, s

SI Base Unit

Time, T

SI Base Quantity

Time divisions began with the earliest civilizations with night and day, then recorded in 2000 BC day and night became twelve hours each. Then after 300 BC, the Babylonians subdivided the day using the sexagesimal system and divided each subsequent subdivision by sixty, then to at least six places after the sexagesimal point, a precision equivalent to 2 microseconds.

The first use of the second was in 1000 AD by a Persian scholar Al-Biruni and defined the division of time between new moons of certain specific weeks as a number of days, hours, minutes, seconds, thirds, and fourths after noon Sunday. The modern second is subdivided using decimals and the earliest clocks to display seconds appeared post 1560 AD on an unsigned clock depicting Orpheus in the Fremersdorf collection. In 1644 AD, Marin Mersenne, calculated that a pendulum with a length of 39.1 inches (0.994 m) would have a period at one standard gravity of precisely two seconds, one second for a swing forward and one second for the return swing, enabling a pendulum to tick in precise seconds.

In 1832, mathematician and physicist, Johann Carl Friedrich Gauss proposed using the second as the base unit of time in his millimetre-milligram-second system of units, defining the second as 1⁄86,400 of a mean solar day. In 1956, the second was redefined in terms of a year (the period of the Earth’s revolution around the Sun) for a particular epoch, described in Newcomb’s Tables of the Sun (1895), which provided a formula for estimating the motion of the Sun relative to the epoch 1900 based on astronomical observations made between 1750 and 1892.

In 1960, the second was defined as 1⁄31,556,925.974’7 of the tropical year for 1900 January 0 at 12-hour ephemeris time, abandoning any explicit relationship between the scientific second and the length of a day.

Formally, as defined in 2014:
“The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.”

Proposed:
“The second, s, is the unit of time; its magnitude is set by fixing the numerical value of the ground state hyperfine splitting frequency of the caesium-133 atom, at rest and at a temperature of 0 K, to be equal to exactly 9,192,631,770 when it is expressed in the unit s−1, which is equal to Hz.”

Invented by Claudius Ptolemy, 150 AD

Second S

Second, s

SI Base Unit

Time, T

SI Base Quantity

Time divisions began with the earliest civilizations with night and day, then recorded in 2000 BC day and night became twelve hours each. Then after 300 BC, the Babylonians subdivided the day using the sexagesimal system and divided each subsequent subdivision by sixty, then to at least six places after the sexagesimal point, a precision equivalent to 2 microseconds.

The first use of the second was in 1000 AD by a Persian scholar Al-Biruni and defined the division of time between new moons of certain specific weeks as a number of days, hours, minutes, seconds, thirds, and fourths after noon Sunday. The modern second is subdivided using decimals and the earliest clocks to display seconds appeared post 1560 AD on an unsigned clock depicting Orpheus in the Fremersdorf collection. In 1644 AD, Marin Mersenne, calculated that a pendulum with a length of 39.1 inches (0.994 m) would have a period at one standard gravity of precisely two seconds, one second for a swing forward and one second for the return swing, enabling a pendulum to tick in precise seconds.

In 1832, mathematician and physicist, Johann Carl Friedrich Gauss proposed using the second as the base unit of time in his millimetre-milligram-second system of units, defining the second as 1⁄86,400 of a mean solar day. In 1956, the second was redefined in terms of a year (the period of the Earth’s revolution around the Sun) for a particular epoch, described in Newcomb’s Tables of the Sun (1895), which provided a formula for estimating the motion of the Sun relative to the epoch 1900 based on astronomical observations made between 1750 and 1892.

In 1960, the second was defined as 1⁄31,556,925.974’7 of the tropical year for 1900 January 0 at 12-hour ephemeris time, abandoning any explicit relationship between the scientific second and the length of a day.

Formally, as defined in 2014:
“The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.”

Proposed:
“The second, s, is the unit of time; its magnitude is set by fixing the numerical value of the ground state hyperfine splitting frequency of the caesium-133 atom, at rest and at a temperature of 0 K, to be equal to exactly 9,192,631,770 when it is expressed in the unit s−1, which is equal to Hz.”

Invented by
Claudius Ptolemy, 150 AD

Secure Hash Algorithm S

Message digest algorithm developed by the NSA for use in the Digital Signature standard, FIPS number 186 from NIST. SHA is an improved variant of MD4 producing a 160-bit hash. SHA is one of two message digest algorithms available in IPSEC.

Semiconductor S

Material that has a function that differ from an electrical conductors or insulators. Examples include silicon, germanium, gallium and also elements within groups III and V of the periodic table of chemical elements. Components made from these elements include: diodes, transistors, thyristors, and integrated circuits.

Shift Register S

Two or more bistable elements (flip-flops) connected in series and with each tick of the clock, the output of stage n is shifted to stage n+1. Applications include clock or signal delays, delay lines, linear-feedback shift registers.

SI Prefixes (Binary) S

N S K P D

Yobi Yi Yottabinary (2¹⁰)⁸ 1,208,925,819,614,629,174,706,176

Zebi Zi Zettabinary (2¹⁰)⁷ 1,180,591,620,717,411,303,424

Exbi Ei Exabinary (2¹⁰)⁶ 1,152,921,504,606,850,000

Pebi Pi Petabinary (2¹⁰)⁵ 1,125,899,906,842,620

Tebi Ti Terabinary (2¹⁰)⁴ 1,099,511,627,776

Gibi Gi Gigabinary (2¹⁰)³ 1,073,741,824

Mebi Mi Megabinary (2¹⁰)² 1,048,576

Kibi Ki Kilobinary (2¹⁰)¹ 1,024

Unit 1 One (10⁰) 1

SI Prefixes (Binary) S

N S K P

Yobi Yi Yottabinary (2¹⁰)⁸

Zebi Zi Zettabinary (2¹⁰)⁷

Exbi Ei Exabinary (2¹⁰)⁶

Pebi Pi Petabinary (2¹⁰)⁵

Tebi Ti Terabinary (2¹⁰)⁴

Gibi Gi Gigabinary (2¹⁰)³

Mebi Mi Megabinary (2¹⁰)²

Kibi Ki Kilobinary (2¹⁰)¹

Unit 1 One (10⁰)

SI Prefixes (Decimal) S

N S K P D

Yotta Y Septillion 10²⁴ 1,000,000,000,000,000,000,000,000

Zetta Z Sextillion 10²¹ 1,000,000,000,000,000,000,000

Exa E Quintillion 10¹⁸ 1,000,000,000,000,000,000

Peta P Quadrillion 10¹⁵ 1,000,000,000,000,000

Tera T Trillion 10¹² 1,000,000,000,000

Giga G Billion 10⁹ 1,000,000,000

Mega M Million 10⁶ 1,000,000

Kilo k Thousand 10³ 1,000

Hecto h Hundred 10² 100

Deca da Ten 10¹ 10

Unit 1 One 10⁰ 1

Deci d Tenth 10^-1 0.1

Centi c Hundredth 10^-2 0.01

Milli m Thousandth 10^-3 0.001

Micro μ Millionth 10^-6 0.000’001

Nano n Billionth 10^-9 0.000’000’001

Pico p Trillionth 10^-12 0.000’000’000’001

Femto f Quadrillionth 10^-15 0.000’000’000’000’001

Atto a Quintillionth 10^-18 0.000’000’000’000’000’001

Zepto z Sextillionth 10^-21 0.000’000’000’000’000’000’001

Yocto y Septillionth 10^-24 0.000’000’000’000’000’000’000’001

SI Prefixes (Decimal) S

N S K P

Yotta Y Septillion 10²⁴

Zetta Z Sextillion 10²¹

Exa E Quintillion 10¹⁸

Peta P Quadrillion 10¹⁵

Tera T Trillion 10¹²

Giga G Billion 10⁹

Mega M Million 10⁶

Kilo k Thousand 10³

Hecto h Hundred 10²

Deca da Ten 10¹

Unit 1 One 10⁰

Deci d Tenth 10^-1

Centi c Hundredth 10^-2

Milli m Thousandth 10^-3

Micro μ Millionth 10^-6

Nano n Billionth 10^-9

Pico p Trillionth 10^-12

Femto f Quadrillionth 10^-15

Atto a Quintillionth 10^-18

Zepto z Sextillionth 10^-21

Yocto y Septillionth 10^-24

Siemens S

Siemens, S

SI Derived Unit

Electric Conductance

SI Derived Quantity

kg⁻¹ · m⁻² · s³ · A²

SI Base Expression

This is the unit of electric conductance, electric susceptance and electric admittance which are the reciprocals of resistance, reactance, and impedance. One siemens is equal to the reciprocal of one ohm, and is also referred to as the mho.

Named after Ernst Werner von Siemens

Siemens S

Siemens, S

SI Derived Unit

Electric Conductance

SI Derived Quantity

kg⁻¹ · m⁻² · s³ · A²

SI Base Expression

This is the unit of electric conductance, electric susceptance and electric admittance which are the reciprocals of resistance, reactance, and impedance. One siemens is equal to the reciprocal of one ohm, and is also referred to as the mho.

Named after
Ernst Werner von Siemens

Sieverts S

Sieverts, Sv

SI Derived Unit

Ambient, Directional, Dose and Personal Dose Equivalent

SI Derived Quantity

m² · s⁻²

SI Base Expression

This is a measure of the health effect of low levels of ionizing radiation on the human body. Quantities that are measured in sieverts are intended to represent the stochastic health risk, which for radiation dose assessment is defined as the probability of cancer induction and genetic. The sievert is used for radiation dose quantities such as equivalent dose, effective dose, and committed dose. It is used both to represent the risk of the effect of external radiation from sources outside the body, and the effect of internal irradiation due to inhaled or ingested radioactive substances. One sievert carries with it a 5.5% chance of eventually developing cancer.

Named after Rolf Maximilian Sievert

Sieverts S

Sieverts, Sv

SI Derived Unit

Ambient, Directional, Dose and Personal Dose Equivalent

SI Derived Quantity

m² · s⁻²

SI Base Expression

This is a measure of the health effect of low levels of ionizing radiation on the human body. Quantities that are measured in sieverts are intended to represent the stochastic health risk, which for radiation dose assessment is defined as the probability of cancer induction and genetic. The sievert is used for radiation dose quantities such as equivalent dose, effective dose, and committed dose. It is used both to represent the risk of the effect of external radiation from sources outside the body, and the effect of internal irradiation due to inhaled or ingested radioactive substances. One sievert carries with it a 5.5% chance of eventually developing cancer.

Named after
Rolf Maximilian Sievert

Significant Bit S

In binary notation, the 8-bit byte is a binary number that is translated, by populating additional 0s to the left of the binary number to complete an 8-digit code.

E.g., the decimal number of 43 is = 1 0 1 0 1 1 in binary.

Adding 0s to complete an 8-digit code (in green) = 0 0 1 0 1 0 1 1.

0 0 1 0 1 0 1 1

The Least Significant Bit, LSB of 1, in blue

The Most Significant Bit, MSB of 0, in red

Value of 1 = Negative, 0 = Positive.
If LSB = 1, then the Byte will always be an odd binary number.
If MSB = 1, then the Byte will always be a value of 128 or greater.

Steradian S

Steradian, sr

SI Derived Unit

Solid Angle

SI Derived Quantity

m²/m²

SI Base Expression

Also known as the square radian, it is used in three-dimensional geometry and is analogous to the radian which quantifies planar angles. This solid angle is the ratio between the area subtended and the square of its distance from the vertex: both the numerator and denominator of this ratio have dimension length squared.

SIgnal-to-Noise and Distortion Ratio S

Expressed in decibels, the ratio between the RMS value of the sine wave f(IN) (input sine wave for an ADC, reconstructed output sinewave for a DAC) and the RMS value of the converter noise from DC to the Nyquist frequency, including harmonic content.

Solder S

Used to join components onto printed circuit boards, with a typical soft solder compound that has a typical melting range of 90 to 450 °C. For electrical and electronics work solder wire is available in a range of thicknesses for hand-soldering and with cores containing flux. Certain proportions of an alloy become eutectic and melts at a single temperature and the transition between solidus and liquidus temperatures is where joint quality is greatly affected.

Small Computer System Interface S

Standard for the SCSI interface, define commands, protocols, electrical and optical interfaces. Connection of RAID arrays, tape drives and peripheral devices utilise SCSI, which will be supplanted by the newer USB and IEEE 1341 standards.

Spread Spectrum S

Technology that modulates a signal over many carrier frequencies at once. Used to make transmissions more secure, reduce interference and improve bandwidth-sharing. Spread-spectrum techniques can also be used to reduce electromagnetic interference by dithering the clock frequency so emissions no longer concentrated at one frequency.

Steradian S

Steradian, sr

SI Derived Unit

Solid Angle

SI Derived Quantity

m²/m²

SI Base Expression

Also known as the square radian, it is used in three-dimensional geometry and is analogous to the radian which quantifies planar angles. This solid angle is the ratio between the area subtended and the square of its distance from the vertex: both the numerator and denominator of this ratio have dimension length squared.

Superheterodyne Receiver S

Radio receiver that combines a locally generated frequency with the carrier frequency to produce a lower-frequency signal (IF, or intermediate frequency) that is easier to demodulate than the original modulated carrier.

Surface Acoustic Wave S

Sound wave that propagates along the surface of a solid and is contained within the solid. SAW devices typically combine compressional and shear components. In Wireless applications, SAW refers to a Surface Acoustic Wave band-pass filter, which exhibits much better out-of-band rejection, but has higher passband ripple and insertion loss.

Synchronous Rectification S

Switch-mode power supply design that replaces the “steering” diode with a FET that switches to reduce losses and increase efficiency by ensuring the FET is off during the inductor charge cycle, then switched on as the inductor discharges into the load.

T

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

T

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

T

Tesla T

Tesla, T

SI Derived Unit

Magnetic Flux Density

SI Derived Quantity

kg · s⁻² · A⁻¹

SI Base Expression

This is the measurement for the strength of the magnetic field. One tesla is equal to one weber per square metre. A particle, that is carrying the charge of 1 coulomb, passing through a magnetic field of 1 tesla, perpendicular and at a speed of 1 metre per second, experiences a force of magnitude 1 newton.

Named after Nicola Tesla

Tesla T

Tesla, T

SI Derived Unit

Magnetic Flux Density

SI Derived Quantity

kg · s⁻² · A⁻¹

SI Base Expression

This is the measurement for the strength of the magnetic field. One tesla is equal to one weber per square metre. A particle, that is carrying the charge of 1 coulomb, passing through a magnetic field of 1 tesla, perpendicular and at a speed of 1 metre per second, experiences a force of magnitude 1 newton.

Named after
Nicola Tesla

Tin Whiskers T

Microscopic, conductive, hair-like crystals that emanate spontaneously from pure tin surfaces and have also been found on alloys and can form in any environment.

Total Harmonic Distortion T

Measure of signal distortion which assesses the energy that occurs on harmonics of the original signal, specified as a percentage of signal amplitude. As an example, if a 12kHz signal is applied to the input, THD would look at energy on the output occurring at 24kHz, 36kHz, 48kHz, etc. and compare it to the energy occurring at 12kHz.

Totem Pole T

Standard CMOS output structure where a P-channel MOSFET is connected in series with an N-Channel MOSFET and the connection point between the two is the output. When the signal is low, the P-FET is on; when the signal is high, the N-FET is on, creating an oscillating push-pull output using just two transistors.

Transmission Control Protocol/Internet Protocol T

Multiple communications protocols used to connect hosts on the Internet and is built into the UNIX operating system, making it the de facto standard for transmitting data over networks. The foundational protocols are the Transmission Control Protocol (TCP) and the Internet Protocol (IP) and is also known as the DoD model, developed by DARPA.

The Internet protocol suite provides end-to-end data communication that specify how data is received, addressed, packeted, routed, and transmitted. There are four abstraction layers for all related protocols: the lowest, the link layer, is a single network link that contains communication methods; the internet layer, provides connections between independent networks; the transport layer handles host-to-host communication; and the application layer, provides application, process-to-process data exchange.

U

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

U

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

U

Uniform Resource Locator U

SYNTAX:
[//[user:password@]host[:port]][/]path[?query][#fragment] Reference link to a web resource that specifies its location on a computer network and a mechanism for retrieving it. A URL is a specific type of Uniform Resource Identifier, most commonly to reference web pages (http), but are also used for file transfer (ftp), email (mailto) and database access (JDBC). Most web browsers display the URL of a web page above the page in an address bar. A typical URL could have the form: www.centraldatacore.com/Readme-Example.pdf, which indicates a protocol: (https://), a hostname: (www.centraldatacore.com), and a file name (readme.pdf).

Universal Asynchronous Receiver-Transmitter U

Integrated circuit that converts parallel data to serial for transmission; and converts received serial data to parallel data.

Universal Serial Bus U

Communication standard that was developed as a replacement for the RS-232 interface, allowing for simpler connection and handshake of peripheral and external devices such as: digital cameras, scanners, keyboards, and mice.

DATARATES expressed as bits per second (bit/s) and bytes per second (B/s)

USB versions 0.8, 0.9, 0.99, 1.0 and 1.1 at 12 Mbit/s (1.5 MB/s)
USB 2.0 at 480 Mbit/s (60 MB/s)
USB 3.0 at 5 Gbit/s (625 MB/s)
USB 3.1 at 10 Gbit/s (1.25 GB/s).

V

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

V

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

V

Volt V

Volt, V

SI Derived Unit

Electric Potential Difference, Electromotive Force

SI Derived Quantity

kg · m² · s⁻³ · A⁻¹

SI Base Expression

This is the measurement for the strength of the magnetic field. One tesla is equal to one weber per square metre. A particle, that is carrying the charge of 1 coulomb, passing through a magnetic field of 1 tesla, perpendicular and at a speed of 1 metre per second, experiences a force of magnitude 1 newton.

Named after Alessandro Giuseppe Antonio Anastasio Volta

Volt V

Volt, V

SI Derived Unit

Electric Potential Difference, Electromotive Force

SI Derived Quantity

kg · m² · s⁻³ · A⁻¹

SI Base Expression

This is the measurement for the strength of the magnetic field. One tesla is equal to one weber per square metre. A particle, that is carrying the charge of 1 coulomb, passing through a magnetic field of 1 tesla, perpendicular and at a speed of 1 metre per second, experiences a force of magnitude 1 newton.

Named after
Alessandro Giuseppe Antonio Anastasio Volta

Volt Ampere V

Voltage times the current, feeding into an electrical load in a direct current system or for resistive loads, the wattage and the VA are the same. In a reactive circuit involving inductors and capacitors, the VA will be greater than the average wattage due to phase differences between voltage and current.

Voltage Controlled Oscillator V

Device in which the output frequency is proportional to its input voltage and form two distinct groups based on waveform type:

Linear (harmonic) oscillators are sinusoidal and consist of a resonator with an amplifier that minimises resonator losses and isolates the resonator from the output, examples include LC-tank oscillators and crystal oscillators. In a voltage-controlled oscillator, the voltage input controls frequency, as capacitance from a varactor diode is controlled by applying voltage across the diode.

Relaxation oscillators generate sawtooth or triangular waveforms and are found in monolithic integrated circuits, providing a vast range of frequencies with minimal external components.

Voltage Divider V

Passive linear circuit that divides an output voltage, divided into fractions of input voltages, distributing the input voltage among the components of a divider, as in two resistors connected in series.

Voltage Doubler V

Circuit producing exactly twice the input voltage by charging capacitors then switching with diodes in a charge pump configuration state to alternate and cascade in many orders of magnitude, the voltage of the input.

Voltage Identification Digital V

Circuit developed providing a Central Processing Unit of a computer with a voltage supply value that is requested by a set of digital signals, VID lines, that instruct an on-board power converter to supply a specific voltage level.

Voltage Standing Wave Ratio V

Measure of how efficiently, radio-frequency power is transmitted from a power source, through a transmission line, then into a load. In a perfect system, 100% of energy is transmitted and provides a reference for systems to be measured.

Energy transmitted from a power amplifier through a transmission line, to an antenna, requires an exact match between a source impedance, characteristic impedance of a transmission line and connectors and the load’s impedance. Mismatched impedances cause power to be reflected back to the source and cause destructive interference.

Measuring these voltage variances as a ratio of the highest and lowest voltages along the transmission line, expresses when reflections occur as illustrated in a VSWR ratio. Indication values, e.g., 1.2:1. VSWR = V(max) / V(min) and can also be derived from impedances: VSWR = (1+) / (1-) where Gamma is the voltage reflection coefficient near the load, derived from load impedance (ZL) and source impedance (Zo): = (ZL – Zo) / (ZL + Zo). If load transmission lines are matched = 0 and VSWR = 1.0 (or 1:1).

W

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

W

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

W

Wafer W

Materials created with a wafer pure of crystalline silicon are used for the fabrication of semiconductor components from integrated circuits, transistors, and wafer-based solar cells. The wafer serves as the substrate for microelectronic components built in and over the wafer and undergoes many microfabrication steps from doping or ion implantation, etching, materials deposition and photolithographic patterning. After individual microcircuits are cut and separated from the wafer, they are housed, processed, grading and tested for distribution.

Watchdog W

Feature of supervisory circuits that monitor software execution in a microprocessor or microcontroller, taking appropriate action in a reset or non-maskable interrupt that is triggered in the event of a lockup or an infinite execution loop.

Watt W

Watt, W

SI Derived Unit

Power, Radiant Flux

SI Derived Quantity

kg · m² · s⁻³

SI Base Expression

This unit is defined as joule per second and is used to express the rate of energy conversion or transfer with respect to time.

Named after James Watt

Watt W

Watt, W

SI Derived Unit

Power, Radiant Flux

SI Derived Quantity

kg · m² · s⁻³

SI Base Expression

This unit is defined as joule per second and is used to express the rate of energy conversion or transfer with respect to time.

Named after
James Watt

Watt hour W

Wh, Unit of energy consumed at a rate of one watt, for a period of one hour and equivalent to 3,600 joules.

Webber W

Webber, Wb

SI Derived Unit

Magnetic Flux

SI Derived Quantity

kg · m² · s⁻² · A⁻¹

SI Base Expression

This unit is defined as joule per second and is used to express the rate of energy conversion or transfer with respect to time.

Wheatstone Bridge W

Circuit consisting of four resistors or their equivalent in a series-parallel arrangement that is used to determine the value of an unknown resistance when the other three resistances are known.

Wireless Local Area Network W

Wireless networking with devices based on IEEE 802.11 standards, restricting the use of “Wi-Fi Certified” to products that are successful in interoperability certification testing. Wi-Fi operates with one or a combination of 2.4 gigahertz (12 cm) UHF and 5.8 gigahertz (5 cm) SHF ISM radio bands.

IEEE 802.11 legacy at 2Mbps, IEEE 802.11b at 11Mbps, IEEE 802.11a at 54Mbps, IEEE 802.11g at 54Mbps, IEEE 802.11n at 450Mbps, IEEE 802.11ac1 at 866.7Mbps and IEEE 802.11ac2 at 1.73Gbps.

Worldwide Interoperability for Microwave Access (X) W

Broadband, wireless access mechanism to replace DSL and Cable Modems as defined by the IEEE 802.16 standards.

Wi-Fi (802.11) covers a small area with a radius of a few hundred meters, WiMax (802.16) can cover up to 10 kilometres with only one base station.

X

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

X

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

X

X Crystal Clock Oscillator X

Oscillator that relies on a crystal for its frequency reference and is made from a piezoelectric crystal which oscillates at a very stable frequency.

XAUI X

Ten Gigabit/second network interface that is an innovation of the 10 Gigabit Ethernet Task Force. XAUI is pronounced “Zowie” with the “AUI” portion borrowed from the “Ethernet Attachment Unit Interface” and “X” denoting ten in Roman implying, ten gigabits per second. The XAUI is designed as an interface extender, known as the XGMII, the ten Gigabit Media Independent Interface.

Y

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

Y

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

Y

Yttrium-Iron-Garnet Y

Ferromagnetic material used for solid-state lasers, microwave and optical communications devices.

Z

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

Z

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

Z

Zero Insertion Force Z

Class of IC sockets which clamp the IC pins via a lever to the side of the socket which requires no force affected on the IC or its pins.

#

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

#

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

#

802.11 Legacy #

IEEE standard for WLAN networks operating at 2.4 GHz, bandwidth of 20 MHz.
Data transfer rates of up to 2 Mbits/s.

802.11a #

IEEE standard for WLAN networks operating at 5.0 GHz, bandwidth of 20 MHz.
Data transfer rates of up to 54 Mbits/s.

802.11ac1 #

IEEE standard for WLAN networks operating at 5.0 GHz, bandwidth of up to 80 MHz.
Data transfer rates of up to 866.7 Mbps.

802.11ac2 #

IEEE standard for WLAN networks operating at 5.0 GHz, bandwidth of up to 160 MHz.
Data transfer rates of up to 1.73 Gbps.

802.11b #

IEEE standard for WLAN networks operating at 2.4 GHz, bandwidth of 20 MHz.
Data transfer rates of up to 11 Mbps.

802.11g #

IEEE standard for WLAN networks operating at 2.4 GHz, bandwidth of 20 MHz.
Data transfer rates of up to 54 Mbps.

802.11n #

IEEE standard for WLAN networks operating at 2.4 & 5 GHz, bandwidth of 40 MHz.
Data transfer rates of up to 450 Mbps.

Ω

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

Ω

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

Ω

°C

SI MEASURE

°C, Degrees Celsius

DERIVED UNIT

Celsius Temperature

DERIVED QUANTITY

K

BASE EXPRESSION

°C, Degrees Celsius

DERIVED UNIT

Celsius Temperature

DERIVED QUANTITY

K

BASE EXPRESSION

°C, Degrees Celsius

DERIVED UNIT

Celsius Temperature

DERIVED QUANTITY

K

BASE EXPRESSION

°C, Degrees Celsius

DERIVED UNIT

Celsius Temperature

DERIVED QUANTITY

K

BASE EXPRESSION

°C, Degrees Celsius

DERIVED UNIT

Celsius Temperature

DERIVED QUANTITY

K

BASE EXPRESSION

Celsius, historically known as centigrade, is a scale and unit of measurement for temperature. From 1744 to 1954, 0 °C was defined as the freezing point of water and 100 °C was defined as the boiling point of water, both at a pressure of one standard atmosphere with mercury being the working material. Absolute zero, the lowest temperature possible, is defined as being precisely 0 K and −273.15 °C.

Named after Anders Celsius, Physicist & Mathematician

	Becquerel, Bq SI Derived Unit
	Activity re Radionuclide SI Derived Quantity
	s^-1 SI Base Expression
	This unit is defined as the activity of a quantity of radioactive material in which one nucleus decays per second and is equivalent to an inverse second, s⁻¹. Named after Antoine Henri Becquerel

	Transfer Rate	Performance
Category 1	1 Mbit/s	1 MHz
Category 2	4 Mbit/s	4 MHz
Category 3	10 Mbit/s	16 MHz
Category 4	16 Mbit/s	20 MHz
Category 5	100 Mbit/s	100 MHz
Category 5e	1 Gbit/s	1 Gbit/s
Category 6	10 Gbit/s	250 MHz
Category 6a	10 Gbit/s	500 MHz
Category 7	10 Gbit/s	600 MHz
Category 7a	10 Gbit/s	1 GHz
Category 8	40 Gbit/s	2 GHz

	Transfer Rate	Performance
CAT 1	1 Mbit/s	1 MHz
CAT 2	4 Mbit/s	4 MHz
CAT 3	10 Mbit/s	16 MHz
CAT 4	16 Mbit/s	20 MHz
CAT 5	100 Mbit/s	100 MHz
CAT 5e	1 Gbit/s	1 Gbit/s
CAT 6	10 Gbit/s	250 MHz
CAT 6a	10 Gbit/s	500 MHz
CAT 7	10 Gbit/s	600 MHz
CAT 7a	10 Gbit/s	1 GHz
CAT 8	40 Gbit/s	2 GHz

	Coulomb, C SI Derived Unit
	Electric Charge, Amount of Electricity SI Derived Quantity
	A·s SI Base Expression
	This base unit of electrical charge is equal to 6.25 X 10¹⁸ electrons. Named for Charles Coulomb, the French physicist who pioneered research into magnetism and electricity, whom also formulated Coulomb’s law which states that the force of attraction or repulsion between two charged bodies is equal to the product of the two charges and is inversely proportional to the square of the distance between them. Named after Charles Augustin de Coulomb

	Degrees Celsius, °C SI Derived Unit
	Celsius Temperature SI Derived Quantity
	K SI Base Expression
	Celsius, historically known as centigrade, is a scale and unit of measurement for temperature. From 1744 to 1954, 0 °C was defined as the freezing point of water and 100 °C was defined as the boiling point of water, both at a pressure of one standard atmosphere with mercury being the working material. Absolute zero, the lowest temperature possible, is defined as being precisely 0 K and −273.15 °C. Named after Anders Celsius

	Farad, F SI Derived Unit
	Capacitance SI Derived Quantity
	kg⁻¹·m⁻²·s⁴·A² SI Base Expression
	One farad of capacitance will store one coulomb of charge when the charging force is one volt. Since the farad is a very large unit, capacitance will more commonly expressed as microfarad (uF) or picofarad (pF) values. Named after Michael Faraday

	Gray, Gy SI Derived Unit
	Absorbed Dose, Specific Energy (Imparted), Kerma SI Derived Quantity
	m²·s⁻² SI Base Expression
	This unit is defined as the absorption of one joule of radiation energy per one kilogram of matter. It is used as a measure of absorbed dose, specific energy (imparted), and kerma (an acronym for “kinetic energy released per unit mass”). It is a physical quantity, and does not take into account any biological context. Unlike the pre-1971 non-SI roentgen unit of radiation exposure, the Gray when used for absorbed dose is defined independently of any target material. When measuring kerma the reference target material must be defined explicitly, usually as dry air at standard temperature and pressure. Named after Louis Harold Gray

	Henry, H SI Derived Unit
	Inductance SI Derived Quantity
	kg · m² · s⁻² · A⁻² SI Base Expression
	This is the unit of inductance in which an induced electromotive force of one volt is produced when the current is varied at the rate of one ampere per second. Named after Joseph Henry

	Hertz, Hz SI Derived Unit
	Frequency SI Derived Quantity
	s^-1 SI Base Expression
	This unit of frequency is equal to cycles per second. In defining the second, “the standard to be employed is the transition between the hyperfine levels F = 4, M = 0 and F = 3, M = 0 of the ground state 2S_1/2 of the caesium 133 atom, unperturbed by external fields, and that the frequency of this transition is assigned the value 9,192,631,770 hertz”, effectively defining the hertz and the second simultaneously. Named after Heinrich Hertz

	Joule, J SI Derived Unit
	Energy, Work, Amount of Heat SI Derived Quantity
	kg·m²·s⁻² SI Base Expression
	This is the basic unit of electrical, mechanical, and thermal energy. As a unit of electrical energy it is equal to the energy carried by 1 coulomb of charge being propelled by an electromotive force of 1 volt. Named after Joseph Henry

	Katal, kat SI Derived Unit
	Catalytic Activity SI Derived Quantity
	mol · s^-1 SI Base Expression
	This is a unit for quantifying the catalytic activity of enzymes (measuring the enzymatic activity level in enzyme catalysis) and other catalysts. The katal is not used to express the rate of a reaction; that is expressed in units of concentration per second (or moles per litre per second). It is used to express catalytic activity which is a property of the catalyst.

	Lumen, lm SI Derived Unit
	Luminous Flux SI Derived Quantity
	cd · sr SI Base Expression
	This is a measure of the total “amount” of visible light emitted by a source. Luminous flux differs from power (Radiant Flux) in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light. Radiant flux measurements indicate the total power of all electromagnetic waves emitted, independent of the eye’s ability to perceive it. Lumens are related to lux in that one lux is one lumen per square meter.

	Lux, lx SI Derived Unit
	Illuminance SI Derived Quantity
	cd · sr · m⁻² SI Base Expression
	This is a measure of how much luminous flux (lumens) is spread over a given area. One lux is equal to one lumen per square metre.

	Newton, N SI Derived Unit
	Force SI Derived Quantity
	kg · m · s⁻² SI Base Expression
	Force (F) is any interaction when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity, which includes to begin moving from a state of rest, as in to accelerate. Weight (W) of an object is the force on the object due to gravity. Weight is the product of the mass (m) of the object and the magnitude of the local gravitational acceleration (g), thus: W = mg. Named after Sir Isaac Newton

	Ohm, Ω SI Derived Unit
	Electric Resistance SI Derived Quantity
	kg · m² · s⁻³ · A⁻² SI Base Expression
	The ohm is defined as an electrical resistance between two points of a conductor when a constant potential difference of 1 volt, applied to these points, produces in the conductor a current of 1 ampere, the conductor not being the seat of any electromotive force. In alternating current circuits, electrical impedance is also measured in ohms (Ω). Named after Georg Simon Ohm

	Pascal, Pa SI Derived Unit
	Pressure, Stress SI Derived Quantity
	kg · m^-1 · s⁻² SI Base Expression
	The pascal (Pa), is one newton per square metre. Pressure (P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure. Multiple units of the pascal are the hectopascal (1 hPa ≡ 100 Pa) which is equal to 1 mbar, the kilopascal (1 kPa ≡ 1,000 Pa), the megapascal (1 MPa ≡ 1,000,000 Pa), and the gigapascal (1 GPa ≡ 1,000,000,000 Pa). The unit of measurement called the standard atmosphere (atm) is defined as 101.325 kPa and approximates to the average pressure at sea-level at 45° N. Named after Blaise Pascal

	Radian, rad SI Derived Unit
	Plane Angle SI Derived Quantity
	m/m SI Base Expression
	An angle’s measurement in radians is numerically equal to the length of a corresponding arc of a unit circle; one radian is just under 57.3 degrees (when the arc length is equal to the radius). One radian is equal to 180/π degrees. To convert from radians to degrees, multiply by 180/π. Named after Roger Cotes

N	S	K	P	D
Yobi	Yi	Yottabinary	(2¹⁰)⁸	1,208,925,819,614,629,174,706,176
Zebi	Zi	Zettabinary	(2¹⁰)⁷	1,180,591,620,717,411,303,424
Exbi	Ei	Exabinary	(2¹⁰)⁶	1,152,921,504,606,850,000
Pebi	Pi	Petabinary	(2¹⁰)⁵	1,125,899,906,842,620
Tebi	Ti	Terabinary	(2¹⁰)⁴	1,099,511,627,776
Gibi	Gi	Gigabinary	(2¹⁰)³	1,073,741,824
Mebi	Mi	Megabinary	(2¹⁰)²	1,048,576
Kibi	Ki	Kilobinary	(2¹⁰)¹	1,024
Unit	1	One	(10⁰)	1

N	S	K	P	D
Yotta	Y	Septillion	10²⁴	1,000,000,000,000,000,000,000,000
Zetta	Z	Sextillion	10²¹	1,000,000,000,000,000,000,000
Exa	E	Quintillion	10¹⁸	1,000,000,000,000,000,000
Peta	P	Quadrillion	10¹⁵	1,000,000,000,000,000
Tera	T	Trillion	10¹²	1,000,000,000,000
Giga	G	Billion	10⁹	1,000,000,000
Mega	M	Million	10⁶	1,000,000
Kilo	k	Thousand	10³	1,000
Hecto	h	Hundred	10²	100
Deca	da	Ten	10¹	10
Unit	1	One	10⁰	1
Deci	d	Tenth	10^-1	0.1
Centi	c	Hundredth	10^-2	0.01
Milli	m	Thousandth	10^-3	0.001
Micro	μ	Millionth	10^-6	0.000’001
Nano	n	Billionth	10^-9	0.000’000’001
Pico	p	Trillionth	10^-12	0.000’000’000’001
Femto	f	Quadrillionth	10^-15	0.000’000’000’000’001
Atto	a	Quintillionth	10^-18	0.000’000’000’000’000’001
Zepto	z	Sextillionth	10^-21	0.000’000’000’000’000’000’001
Yocto	y	Septillionth	10^-24	0.000’000’000’000’000’000’000’001

	Siemens, S SI Derived Unit
	Electric Conductance SI Derived Quantity
	kg⁻¹ · m⁻² · s³ · A² SI Base Expression
	This is the unit of electric conductance, electric susceptance and electric admittance which are the reciprocals of resistance, reactance, and impedance. One siemens is equal to the reciprocal of one ohm, and is also referred to as the mho. Named after Ernst Werner von Siemens

INTELLECTUM VIRTUS

INTELLECTUM VIRTUS

INTELLECTUM VIRTUS

INTELLECTUM VIRTUS

INTELLECTUM VIRTUS

ELECTRICAL ENGINEERING

ELECTRICAL ENGINEERING

ELECTRICAL ENGINEERING

ELECTRICAL ENGINEERING

ELECTRICAL ENGINEERING

GLOSSARY OF TERMS

GLOSSARY OF TERMS

GLOSSARY OF TERMS

GLOSSARY OF TERMS

GLOSSARY OF TERMS

DEFINITIONS & FORMULAE

DEFINITIONS & FORMULAE

DEFINITIONS & FORMULAE

DEFINITIONS & FORMULAE

DEFINITIONS & FORMULAE

A A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

A A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

A A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

A A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

A

Adaptive Differential Pulse Code Modulation A Compression technique that encodes only the difference between sequential samples and differs from a DPCM by varying the step size to reduce the required bandwidth for a given signal-to-noise ratio.

Adaptive Differential Pulse Code Modulation A Compression technique that encodes only the difference between sequential samples and differs from a DPCM by varying the step size to reduce the required bandwidth for a given signal-to-noise ratio.

Adaptive Differential Pulse Code Modulation A Compression technique that encodes only the difference between sequential samples and differs from a DPCM by varying the step size to reduce the required bandwidth for a given signal-to-noise ratio.

Adaptive Differential Pulse Code Modulation A Compression technique that encodes only the difference between sequential samples and differs from a DPCM by varying the step size to reduce the required bandwidth for a given signal-to-noise ratio.

Adaptive Differential Pulse Code Modulation A Compression technique that encodes only the difference between sequential samples and differs from a DPCM by varying the step size to reduce the required bandwidth for a given signal-to-noise ratio.

Add / Drop Multiplexer A Synchronous transmission networks carrying multiple channels use this device to prioritise data by inserting (add) or removing (drop) lower-data-rate channel traffic from the higher-rate aggregated channel.

Add / Drop Multiplexer A Synchronous transmission networks carrying multiple channels use this device to prioritise data by inserting (add) or removing (drop) lower-data-rate channel traffic from the higher-rate aggregated channel.

Add / Drop Multiplexer A Synchronous transmission networks carrying multiple channels use this device to prioritise data by inserting (add) or removing (drop) lower-data-rate channel traffic from the higher-rate aggregated channel.

Add / Drop Multiplexer A Synchronous transmission networks carrying multiple channels use this device to prioritise data by inserting (add) or removing (drop) lower-data-rate channel traffic from the higher-rate aggregated channel.

Add / Drop Multiplexer A Synchronous transmission networks carrying multiple channels use this device to prioritise data by inserting (add) or removing (drop) lower-data-rate channel traffic from the higher-rate aggregated channel.

Advanced Configuration and Power Interface A Industry-standard specification, co-developed by Hewlett-Packard, Intel, Microsoft, Phoenix and Toshiba, for operating-system-directed power management for laptop, desktop, and server computers.

Advanced Configuration and Power Interface A Industry-standard specification, co-developed by Hewlett-Packard, Intel, Microsoft, Phoenix and Toshiba, for operating-system-directed power management for laptop, desktop, and server computers.

Advanced Configuration and Power Interface A Industry-standard specification, co-developed by Hewlett-Packard, Intel, Microsoft, Phoenix and Toshiba, for operating-system-directed power management for laptop, desktop, and server computers.

Advanced Configuration and Power Interface A Industry-standard specification, co-developed by Hewlett-Packard, Intel, Microsoft, Phoenix and Toshiba, for operating-system-directed power management for laptop, desktop, and server computers.

Advanced Configuration and Power Interface A Industry-standard specification, co-developed by Hewlett-Packard, Intel, Microsoft, Phoenix and Toshiba, for operating-system-directed power management for laptop, desktop, and server computers.

Advanced Power Management A Power management standard for computers that provides five power states: Ready, Stand-by, Suspended, Hibernation and Off.

Advanced Power Management A Power management standard for computers that provides five power states: Ready, Stand-by, Suspended, Hibernation and Off.

Advanced Power Management A Power management standard for computers that provides five power states: Ready, Stand-by, Suspended, Hibernation and Off.

Advanced Power Management A Power management standard for computers that provides five power states: Ready, Stand-by, Suspended, Hibernation and Off.

Advanced Power Management A Power management standard for computers that provides five power states: Ready, Stand-by, Suspended, Hibernation and Off.

Discovered by Nicola Tesla, 1886

Discovered by Nicola Tesla, 1886

Discovered by Nicola Tesla, 1886

Discovered by Nicola Tesla, 1886

Discovered by Nicola Tesla, 1886

Invented by Joseph Rodgers, 1857

Invented by Joseph Rodgers, 1857

Invented by Joseph Rodgers, 1857

Invented by Joseph Rodgers, 1857

Invented by Joseph Rodgers, 1857

Discovered by Arthur Edwin Kennelly, 1895

Discovered by Arthur Edwin Kennelly, 1895

Discovered by Arthur Edwin Kennelly, 1895

Discovered by Arthur Edwin Kennelly, 1895

Discovered by Arthur Edwin Kennelly, 1895

SI Base Unit

SI Base Quantity

Discovered by André-Marie Ampère, 1820

SI Base Unit

SI Base Quantity

Discovered by André-Marie Ampère, 1820

SI Base Unit

SI Base Quantity

Discovered by André-Marie Ampère, 1820

SI Base Unit

SI Base Quantity

Discovered by André-Marie Ampère, 1820

SI Base Unit

SI Base Quantity

Discovered by André-Marie Ampère, 1820

Ampere-hour A Measurement of the current capacity or rate of usage of an electrical supply, in Ampere-hours, Ah and describes the use of one amp of current, flowing for a duration of one hour or 3,600 coulombs.

Ampere-hour A Measurement of the current capacity or rate of usage of an electrical supply, in Ampere-hours, Ah and describes the use of one amp of current, flowing for a duration of one hour or 3,600 coulombs.

Ampere-hour A Measurement of the current capacity or rate of usage of an electrical supply, in Ampere-hours, Ah and describes the use of one amp of current, flowing for a duration of one hour or 3,600 coulombs.

Ampere-hour A Measurement of the current capacity or rate of usage of an electrical supply, in Ampere-hours, Ah and describes the use of one amp of current, flowing for a duration of one hour or 3,600 coulombs.

Ampere-hour A Measurement of the current capacity or rate of usage of an electrical supply, in Ampere-hours, Ah and describes the use of one amp of current, flowing for a duration of one hour or 3,600 coulombs.

A

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ω

A

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

A

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

A

A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z # Ω

Adaptive Differential Pulse Code Modulation A

Compression technique that encodes only the difference between sequential samples and differs from a DPCM by varying the step size to reduce the required bandwidth for a given signal-to-noise ratio.

Adaptive Differential Pulse Code Modulation A

Compression technique that encodes only the difference between sequential samples and differs from a DPCM by varying the step size to reduce the required bandwidth for a given signal-to-noise ratio.

Adaptive Differential Pulse Code Modulation A

Compression technique that encodes only the difference between sequential samples and differs from a DPCM by varying the step size to reduce the required bandwidth for a given signal-to-noise ratio.

Adaptive Differential Pulse Code Modulation A

Compression technique that encodes only the difference between sequential samples and differs from a DPCM by varying the step size to reduce the required bandwidth for a given signal-to-noise ratio.

Adaptive Differential Pulse Code Modulation A

Compression technique that encodes only the difference between sequential samples and differs from a DPCM by varying the step size to reduce the required bandwidth for a given signal-to-noise ratio.

Add / Drop Multiplexer A

Synchronous transmission networks carrying multiple channels use this device to prioritise data by inserting (add) or removing (drop) lower-data-rate channel traffic from the higher-rate aggregated channel.

Add / Drop Multiplexer A

Synchronous transmission networks carrying multiple channels use this device to prioritise data by inserting (add) or removing (drop) lower-data-rate channel traffic from the higher-rate aggregated channel.

Add / Drop Multiplexer A

Synchronous transmission networks carrying multiple channels use this device to prioritise data by inserting (add) or removing (drop) lower-data-rate channel traffic from the higher-rate aggregated channel.

Add / Drop Multiplexer A

Synchronous transmission networks carrying multiple channels use this device to prioritise data by inserting (add) or removing (drop) lower-data-rate channel traffic from the higher-rate aggregated channel.

Add / Drop Multiplexer A

Synchronous transmission networks carrying multiple channels use this device to prioritise data by inserting (add) or removing (drop) lower-data-rate channel traffic from the higher-rate aggregated channel.

Advanced Configuration and Power Interface A

Industry-standard specification, co-developed by Hewlett-Packard, Intel, Microsoft, Phoenix and Toshiba, for operating-system-directed power management for laptop, desktop, and server computers.

Advanced Configuration and Power Interface A

Industry-standard specification, co-developed by Hewlett-Packard, Intel, Microsoft, Phoenix and Toshiba, for operating-system-directed power management for laptop, desktop, and server computers.

Advanced Configuration and Power Interface A

Industry-standard specification, co-developed by Hewlett-Packard, Intel, Microsoft, Phoenix and Toshiba, for operating-system-directed power management for laptop, desktop, and server computers.

Advanced Configuration and Power Interface A

Industry-standard specification, co-developed by Hewlett-Packard, Intel, Microsoft, Phoenix and Toshiba, for operating-system-directed power management for laptop, desktop, and server computers.

Advanced Configuration and Power Interface A

Industry-standard specification, co-developed by Hewlett-Packard, Intel, Microsoft, Phoenix and Toshiba, for operating-system-directed power management for laptop, desktop, and server computers.

Advanced Power Management A

Power management standard for computers that provides five power states: Ready, Stand-by, Suspended, Hibernation and Off.

Advanced Power Management A

Power management standard for computers that provides five power states: Ready, Stand-by, Suspended, Hibernation and Off.

Advanced Power Management A

Power management standard for computers that provides five power states: Ready, Stand-by, Suspended, Hibernation and Off.

Advanced Power Management A

Power management standard for computers that provides five power states: Ready, Stand-by, Suspended, Hibernation and Off.

Advanced Power Management A

Power management standard for computers that provides five power states: Ready, Stand-by, Suspended, Hibernation and Off.

Discovered by
Nicola Tesla, 1886

Discovered by
Nicola Tesla, 1886

Discovered by
Nicola Tesla, 1886

Discovered by
Nicola Tesla, 1886

Invented by
Joseph Rodgers, 1857

Invented by
Joseph Rodgers, 1857

Invented by
Joseph Rodgers, 1857

Invented by
Joseph Rodgers, 1857

Discovered by
Arthur Edwin Kennelly, 1895

Discovered by
Arthur Edwin Kennelly, 1895

Discovered by
Arthur Edwin Kennelly, 1895

Discovered by
Arthur Edwin Kennelly, 1895

Discovered by
André-Marie Ampère, 1820

Discovered by
André-Marie Ampère, 1820

Discovered by
André-Marie Ampère, 1820

Discovered by
André-Marie Ampère, 1820

Ampere-hour A

Measurement of the current capacity or rate of usage of an electrical supply, in Ampere-hours, Ah and describes the use of one amp of current, flowing for a duration of one hour or 3,600 coulombs.

Ampere-hour A

Measurement of the current capacity or rate of usage of an electrical supply, in Ampere-hours, Ah and describes the use of one amp of current, flowing for a duration of one hour or 3,600 coulombs.

Ampere-hour A

Measurement of the current capacity or rate of usage of an electrical supply, in Ampere-hours, Ah and describes the use of one amp of current, flowing for a duration of one hour or 3,600 coulombs.

Ampere-hour A

Measurement of the current capacity or rate of usage of an electrical supply, in Ampere-hours, Ah and describes the use of one amp of current, flowing for a duration of one hour or 3,600 coulombs.

Ampere-hour A

Measurement of the current capacity or rate of usage of an electrical supply, in Ampere-hours, Ah and describes the use of one amp of current, flowing for a duration of one hour or 3,600 coulombs.

Amplitude Modulation A

Method of transmitting information via a radio carrier wave by the amplitude (signal strength) of the carrier wave being varied in proportion to the waveform being transmitted.

Invented by Reginald Fessenden, 1900

Amplitude Modulation A

Method of transmitting information via a radio carrier wave by the amplitude (signal strength) of the carrier wave being varied in proportion to the waveform being transmitted.

Invented by
Reginald Fessenden, 1900

Invented by
Reginald Fessenden, 1900

Amplitude Modulation A

Method of transmitting information via a radio carrier wave by the amplitude (signal strength) of the carrier wave being varied in proportion to the waveform being transmitted.

Invented by
Reginald Fessenden, 1900

Invented by
Reginald Fessenden, 1900

Amplitude Modulation A

Method of transmitting information via a radio carrier wave by the amplitude (signal strength) of the carrier wave being varied in proportion to the waveform being transmitted.

Invented by
Reginald Fessenden, 1900

Invented by
Reginald Fessenden, 1900

Amplitude Modulation A

Method of transmitting information via a radio carrier wave by the amplitude (signal strength) of the carrier wave being varied in proportion to the waveform being transmitted.

Invented by
Reginald Fessenden, 1900

Invented by
Reginald Fessenden, 1900

Analogue A

Refers to signals, circuits and systems that are natural and not digitally translated as in speech or the amplification of waveforms from past radio or television transmissions.

Analogue A

Refers to signals, circuits and systems that are natural and not digitally translated as in speech or the amplification of waveforms from past radio or television transmissions.

Analogue A

Refers to signals, circuits and systems that are natural and not digitally translated as in speech or the amplification of waveforms from past radio or television transmissions.

Analogue A

Refers to signals, circuits and systems that are natural and not digitally translated as in speech or the amplification of waveforms from past radio or television transmissions.

Analogue A

Refers to signals, circuits and systems that are natural and not digitally translated as in speech or the amplification of waveforms from past radio or television transmissions.

Analogue Front End A

Analogue portion of a circuit which precedes A/D conversion.

Analogue Front End A

Analogue portion of a circuit which precedes A/D conversion.

Analogue Front End A

Analogue portion of a circuit which precedes A/D conversion.

Analogue Front End A

Analogue portion of a circuit which precedes A/D conversion.

Analogue Front End A

Analogue portion of a circuit which precedes A/D conversion.

Angstrom A

1 Å = 10-10 m = 0.1 nm = 100pm

Angstrom A

1 Å = 10-10 m = 0.1 nm = 100pm

Angstrom A

1 Å = 10-10 m = 0.1 nm = 100pm

Angstrom A

1 Å = 10-10 m = 0.1 nm = 100pm

Angstrom A

1 Å = 10-10 m = 0.1 nm = 100pm

Annular Ring A

Conductive material surrounding a hole drilled in a printed circuit board, used for pads, vias and mounting holes.

Invented by Paul Eisler, 1943

Annular Ring A

Conductive material surrounding a hole drilled in a printed circuit board, used for pads, vias and mounting holes.

Invented by
Paul Eisler, 1943

Invented by
Paul Eisler, 1943

Annular Ring A

Conductive material surrounding a hole drilled in a printed circuit board, used for pads, vias and mounting holes.

Invented by
Paul Eisler, 1943

	Sieverts, Sv SI Derived Unit
	Ambient, Directional, Dose and Personal Dose Equivalent SI Derived Quantity
	m² · s⁻² SI Base Expression
	This is a measure of the health effect of low levels of ionizing radiation on the human body. Quantities that are measured in sieverts are intended to represent the stochastic health risk, which for radiation dose assessment is defined as the probability of cancer induction and genetic. The sievert is used for radiation dose quantities such as equivalent dose, effective dose, and committed dose. It is used both to represent the risk of the effect of external radiation from sources outside the body, and the effect of internal irradiation due to inhaled or ingested radioactive substances. One sievert carries with it a 5.5% chance of eventually developing cancer. Named after Rolf Maximilian Sievert

	Steradian, sr SI Derived Unit
	Solid Angle SI Derived Quantity
	m²/m² SI Base Expression
	Also known as the square radian, it is used in three-dimensional geometry and is analogous to the radian which quantifies planar angles. This solid angle is the ratio between the area subtended and the square of its distance from the vertex: both the numerator and denominator of this ratio have dimension length squared.

	Tesla, T SI Derived Unit
	Magnetic Flux Density SI Derived Quantity
	kg · s⁻² · A⁻¹ SI Base Expression
	This is the measurement for the strength of the magnetic field. One tesla is equal to one weber per square metre. A particle, that is carrying the charge of 1 coulomb, passing through a magnetic field of 1 tesla, perpendicular and at a speed of 1 metre per second, experiences a force of magnitude 1 newton. Named after Nicola Tesla

	Volt, V SI Derived Unit
	Electric Potential Difference, Electromotive Force SI Derived Quantity
	kg · m² · s⁻³ · A⁻¹ SI Base Expression
	This is the measurement for the strength of the magnetic field. One tesla is equal to one weber per square metre. A particle, that is carrying the charge of 1 coulomb, passing through a magnetic field of 1 tesla, perpendicular and at a speed of 1 metre per second, experiences a force of magnitude 1 newton. Named after Alessandro Giuseppe Antonio Anastasio Volta

	Watt, W SI Derived Unit
	Power, Radiant Flux SI Derived Quantity
	kg · m² · s⁻³ SI Base Expression
	This unit is defined as joule per second and is used to express the rate of energy conversion or transfer with respect to time. Named after James Watt

	Webber, Wb SI Derived Unit
	Magnetic Flux SI Derived Quantity
	kg · m² · s⁻² · A⁻¹ SI Base Expression
	This unit is defined as joule per second and is used to express the rate of energy conversion or transfer with respect to time.