- #1

- 443

- 27

Assuming the electron is a sphere of finite extent, the classical electron radius is derived by equating the energy of the electric field with m

_{e}c

^{2}. For the computation of the field energy, we have to assume a charge distribution. Both constant charge density and constant surface density lead to prefactors (3/5 or 1/2) which are somehow just ignored.

Why? If we are only interested in the order of magnitude, why drop these prefactors but keep 1/4?