The so-called "classical" electron radius , also called the Compton radius, is defined in cgs by
equating the electrostatic potential energy of a sphere of charge e and radius with the rest energy of
the electron,
where is the charge on the electron, is the electron mass, and c is the speed of light.
Solving for gives
Similarly in MKS,
where is the permittivity of free space.
Numerically,
Electron, Point Charge
© 1996-2007 Eric W. Weisstein
