Physics Study Guide/Greek alphabet

About the Common uses in Physics

While these are indeed common usages, it should be pointed out that there are many other usages and that other letters are used for the same purpose. The reason is quite simple: there are only so many symbols in the Greek and Latin alphabets, and scientists and mathematicians generally do not use symbols from other languages. It is a common trap to associate a symbol exclusively with some particular meaning, rather than learning and understanding the physics and relations behind it.

Greek Alphabet

Capital	Lower case	Name	Common use in Physics
Template:Math	Template:Math	alpha	Angular acceleration Linear expansion Coefficient Alpha particle (helium nucleus) Fine Structure Constant
Template:Math	Template:Math	beta	Beta particle — high energy electron Sound intensity
Template:Math	Template:Math	gamma	Gamma ray (high energy EM wave) Ratio of heat capacities (in an ideal gas) Relativistic correction factor Shear strain
Template:Math	Template:Math	delta	Δ="Change in" δ="Infinitesimal change in (), also used to denote the Dirac delta function (reference needed)"
Template:Math	Template:Math	epsilon	Emissivity Strain (Direct e.g. tensile or compression) Permittivity EMF
Template:Math	Template:Math	zeta	(no common use)
Template:Math	Template:Math	eta	Viscosity Energy efficiency
Template:Math	Template:Math	theta	Angle (°, rad) Temperature
Template:Math	Template:Math	iota	The lower case $\iota$ is rarely used, while $\mathrm{I}$ is sometimes used for the identity matrix or the moment of inertia. Note that $\iota$ is not to be confused with the Roman character $i$ (which has a dot and is much more widely used in mathematics and physics).
Template:Math	Template:Math	kappa	Spring constant Dielectric constant
Template:Math	Template:Math	lambda	Wavelength Thermal conductivity Constant Eigenvalue of a matrix Linear density
Template:Math	Template:Math	mu	Coefficient of friction Electrical mobility Reduced mass Permeability
Template:Math	Template:Math	nu	Frequency
Template:Math	Template:Math	xi	Damping cofficient
Template:Math	Template:Math	omicron	(no common use)
Template:Math	Template:Math	pi	Product symbol $\mathrm{\Pi }$ Circle number $\pi :=3.14159...$
Template:Math	Template:Math	rho	Volume density Resistivity
Template:Math	Template:Math	sigma	Sum symbol Boltzmann constant Electrical conductivity Uncertainty Stress (Direct e.g. tensile, compression) Surface density
Template:Math	Template:Math	tau	Torque Tau particle (a lepton) Time constant Shear stress
Template:Math	Template:Math	upsilon	mass to light ratio
Template:Math	Template:Math	phi	Magnetic/electric flux Angle (°, rad)
Template:Math	Template:Math	chi	Rabi frequency (lasers) Susceptibility Mole Fraction
Template:Math	Template:Math	psi	Wave function
Template:Math	Template:Math	omega	Ohms (unit of electrical resistance) ω Angular velocity

See Also

Greek alphabet on Wikipedia

Greek letters used in mathematics, science, and engineering Template:BookCat