Wikipedia:WikiProject Electronics/Standard symbols

From Wikipedia, the free encyclopedia

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.

Contents

[edit] Waves and Waveforms

Symbol Meaning SI Units of Measure
\ f \ frequency hertz (cycles/second)
\ \omega \ angular frequency radians per second
\ k \ wave number radians per meter
\ \lambda \ wavelength meters per cycle
\ T \ period seconds per cycle

[edit] Optics and Photonics

Symbol Meaning SI Units of Measure
\ n \ refractive index dimensionless
\ c_0 \ speed of light in vacuum meters per second
\ c \ speed of light in material medium meters per second
\ \nu \ frequency hertz (cycles/second)
\ \omega \ angular frequency radians per second
\ k \ wave number radians per meter
\ \lambda \ wavelength meters per cycle
\ R \ radius of curvature meters
\Gamma \ reflection coefficient dimensionless
\alpha \ absorption coefficient dimensionless
\mathcal{R} \ reflectivity dimensionless
\mathcal{T} \ transmissivity dimensionless

[edit] Electromagnetics

Symbol Meaning SI Units of Measure
\mathbf{E} Electric field volts per meter
\mathbf{H} Magnetic field amperes per meter
\mathbf{D} Electric displacement coulombs per square meter
\mathbf{B} Magnetic flux density tesla or
webers per square meter
\Phi_\mathbf{D} Electric flux voltmeters
\Phi_\mathbf{B} Magnetic flux webers
\mathbf{P} Polarization density coulombs per square meter
\mathbf{M} Magnetization amperes per meter
\mathbf{J} Current density amperes per square meter
\ \varepsilon \ Electric permittivity farads per meter
\ \mu \ Magnetic permeability henries per meter
\ \sigma \ conductivity siemens per meter
\ \chi \ susceptibility dimensionless
\ q \ Electric charge coulombs
\ \rho \ Electric charge density coulombs per cubic meter
\ \Phi \ Electric potential volts
\ \Psi \ Magnetic scalar potential amperes
\mathbf{A} Magnetic vector potential webers per meter

[edit] Electrical Circuits

Symbol Meaning SI Units of Measure
\ i \ electric current amperes
\ v \ voltage or electric potential difference volts
\ I \ electric current complex amplitude coulombs
\ V \ voltage complex amplitude webers
\ R \ Resistance ohms
\ G \ Conductance siemens or mhos
\ C \ Capacitance farads
\ L \ Inductance henries
\ Z \ Impedance ohms
\ X \ Reactance ohms
\ Y \ Admittance siemens or mhos
\ r \ radius meters

[edit] Signals and Systems

Symbol Meaning SI Units of Measure
\ t \ time seconds
\ j \ the imaginary unit dimensionless
\ e \ base of the natural logarithm
2.71828...		 dimensionless
\ \pi \ ratio of the circumference
to the diameter of a circle
3.1415927...		 dimensionless
\ \tau \ time constant seconds
\ \alpha \ exponential decay constant nepers per second (1/second)
\ \theta \ instantaneous angle in argument of sinusoid radians (dimensionless)
\ \phi \ phase angle radians (dimensionless)
\ Q \ quality factor dimensionless
\ \Delta f \ Bandwidth hertz
\ \zeta \ damping factor dimensionless
\ \rho_{x y} \ Correlation between x and y dimensionless
\ \sigma_x \ Standard deviation of x same units as x
\ \overline{x} \ Mean value of x same units as x
\ E(X) \ Expected value of the random variable X same units as X
\ \mu_n \ nth moment of a function nth power of the domain's units
\ \Phi (\omega) \ Spectral density joules per hertz/watts per hertz