Field and Wave Electromagnetics 2nd Edition by David Cheng

Exercise 22

Einstein's theory of relativity stip ulates that the work required to assemble a charge is stored as energy in the mass and is equal to mc 2 , where m is the mass and c 3 × 10 8 (m/s) is the velocity of light. Assuming the electron to be a perfect sphere, find its radius from its charge and mass (9.1 × 10 -31 kg).