# Physics Study Guide/Greek alphabet

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| Physical Constants | Frictional Coefficients | Greek Alphabet | Logarithms | Vectors and Scalars | Other Topics |

# 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 |
| $\mathrm {A}$ | $\alpha$ | alpha | Angular acceleration Linear expansion Coefficient Alpha particle (helium nucleus) Fine Structure Constant |
| $\mathrm {B}$ | $\beta$ | beta | Beta particle — high energy electron Sound intensity |
| $\Gamma$ | $\gamma$ | gamma | Gamma ray (high energy EM wave) Ratio of heat capacities (in an ideal gas) Relativistic correction factor Shear strain |
| $\Delta$ | $\delta$ | delta | Δ="Change in" δ="Infinitesimal change in, also used to denote the Dirac delta function (reference needed)" |
| $\mathrm {E}$ | $\epsilon$ | epsilon | Emissivity Strain (Direct e.g. tensile or compression) Permittivity EMF |
| $\mathrm {Z}$ | $\zeta$ | zeta | (no common use) |
| $\mathrm {H}$ | $\eta$ | eta | Viscosity Energy efficiency |
| $\Theta$ | $\theta$ | theta | Angle (°, rad) Temperature |
| $\mathrm {I}$ | $\iota$ | 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). |
| $\mathrm {K}$ | $\kappa$ | kappa | Spring constant Dielectric constant |
| $\Lambda$ | $\lambda$ | lambda | Wavelength Thermal conductivity Constant Eigenvalue of a matrix Linear density |
| $\mathrm {M}$ | $\mu$ | mu | Coefficient of friction Electrical mobility Reduced mass Permeability |
| $\mathrm {N}$ | $\nu$ | nu | Frequency |
| $\Xi$ | $\xi$ | xi | Damping cofficient |
| $\mathrm {O}$ | $\mathrm {o}$ | omicron | (no common use) |
| $\Pi$ | $\pi$ | pi | Product symbol $\Pi$ Circle number $\pi :=3.14159...$ |
| $\mathrm {P}$ | $\rho$ | rho | Volume density Resistivity |
| $\Sigma$ | $\sigma$ | sigma | Sum symbol Boltzmann constant Electrical conductivity Uncertainty Stress (Direct e.g. tensile, compression) Surface density |
| $\mathrm {T}$ | $\tau$ | tau | Torque Tau particle (a lepton) Time constant Shear stress |
| $\Upsilon$ | $\upsilon$ | upsilon | mass to light ratio |
| $\Phi$ | $\phi$ | phi | Magnetic/electric flux Angle (°, rad) |
| $\mathrm {X}$ | $\chi$ | chi | Rabi frequency (lasers) Susceptibility Mole Fraction |
| $\Psi$ | $\psi$ | psi | Wave function |
| $\Omega$ | $\omega$ | omega | Ohms (unit of electrical resistance) ω Angular velocity |

# See Also

Greek alphabet on Wikipedia
Greek letters used in mathematics, science, and engineering