# Formula Classical Electron Radius Radius    Mass    Elementary charge    Speed of light    Vacuum Permittivity

Unit
Radius of the electron derived in the classical way (i.e., without taking quantum mechanics into account) (although there are several different formulas for the classical electron radius). Note that it is just a theoretical model value and not an experimentally determined quantity!

## Mass

Unit
Rest mass of electron is a physical constant and has the value: $$m_{\text e} ~=~ 9.109 \cdot 10^{-31} \, \text{kg}$$.

## Elementary charge

Unit
Elementary charge is the charge of the electron and has the value: $$e ~=~ 1.602 \cdot 10^{-19} \, \text{C}$$.

## Speed of light

Unit
Speed of light is a physical constant and has the value in vacuum: $$c = 299 \, 792 \, 458 \, \frac{\text m}{\text s}$$.

## Vacuum Permittivity

Unit
Vacuum permittivity is a physical constant with the value: $$\varepsilon_0 = 8.854 \cdot 10^{-12} \, \frac{ \text{As} }{ \text{Vm} }$$.