1. The problem statement, all variables and given/known data If a proton is considered a uniform ball of charge of radius 1.0x10-15m, what is the electric field just beyond its surface? 2. Relevant equations Gauss's law? 3. The attempt at a solution I followed a problem in the book that found an equation for the electric field of a uniformly charged sphere. I treated the proton as a uniform sphere of charge, so that the same equation could be applied. The equation was E = (1/4piE0)(Q/r^2) *E0 is constant 8.85 x 10^-12. So I just plugged in charge of electron and radius r of the proton.