Question: A stationary electron is a point of charge. What is the energy density of U, it's electric field at a radial distance r=1mm?
Know:
1mm=1*10^-3m
u=(1/2)(epsilon naught)(E^2)
E=kq/r^2
I know I have to end up solving for (E)^2, where E=kq/r^2, but how do I determine what charge to use...