Wikipedia:WikiProject Electronics/Standard symbols

Reference should be made to codes and standards. For example, IEC 60027, and Letter Symbols in Electrical Technology.

Here are tables of widely accepted symbols. They are meant to be a guideline: Using the same symbols for the same things in different articles will increase their consistency, making them easier to understand and to improve. If you are looking for the symbol for something that is not on the list, just check whether a particular symbol has been already chosen, and create your own. If anybody will disagree with it, discuss it on the talk page.

It is certainly not an exhaustive list, nor is it in any particular order.

Waves and waveforms

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Symbol Meaning SI Units of Measure
  frequency hertz (cycles per second)
  angular frequency radians per second
  wave number radians per meter
  wavelength meters per cycle
  period seconds per cycle

Optics and photonics

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Symbol Meaning SI Units of Measure
  refractive index dimensionless
  speed of light in vacuum meters per second
  speed of light in material medium meters per second
  frequency hertz (cycles per second)
  angular frequency radians per second
  wave number radians per meter
  wavelength meters per cycle
  radius of curvature meters
  reflection coefficient dimensionless
  absorption coefficient dimensionless
  reflectivity dimensionless
  transmissivity dimensionless

Electromagnetics

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Symbol Meaning SI Units of Measure
  Electric field volts per meter
  Magnetic field amperes per meter
  Electric displacement coulombs per square meter
  Magnetic flux density teslas or
webers per square meter
  Electric flux voltmeters
  Magnetic flux webers
  Polarization density coulombs per square meter
  Magnetization amperes per meter
  Current density amperes per square meter
  Electric permittivity farads per meter
  Magnetic permeability henries per meter
  conductivity siemens per meter
  susceptibility dimensionless
  Electric charge coulombs
  Electric charge density coulombs per cubic meter
  Electric potential volts
  Magnetic scalar potential amperes
  Magnetic vector potential webers per meter

R} Resistance of " R"

Electrical circuits

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Symbol Meaning SI Units of Measure
  Susceptance siemens
  Capacitance farad
  Conductance siemens
  Inductance henry
  Current ampere
  Alternating Current ampere
  Power Watt
  Reactive Power Volt-Ampere Reactive
  Resistance ohm
  Apparent Power Volt-Ampere
  Voltage volt
  Alternating Voltage volt
  Reactance ohm
  Admittance siemens
  Impedance ohm

Signals and systems

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Symbol Meaning SI Units of Measure
  time seconds
  the imaginary unit dimensionless
  base of the natural logarithm
2.71828...
dimensionless
  ratio of the circumference
to the diameter of a circle
3.1415927...
dimensionless
  time constant seconds
  exponential decay constant
or attenuation coefficient
nepers per second (1/second)
  instantaneous angle in argument of sinusoid radians (dimensionless)
  phase angle radians (dimensionless)
  quality factor dimensionless
  Bandwidth hertz
  damping factor dimensionless
  Correlation between x and y dimensionless
  Standard deviation of x same units as x
  Mean value of x same units as x
  Expected value of the random variable X same units as X
  nth moment of a function nth power of the domain's units
  Autocorrelation of random process X(t) watts
  Power spectral density of random process X(t) watts per hertz