1. The problem statement, all variables and given/known data If we take the average radius of the electron wave function in the ground state of hydrogen to be the Bohr radius, calculate the average potential energy of the electron due to the Coulomb interaction with the nucleus. State answer in eV. 2. Relevant equations I think the relevant equation is V(x)= -(e^2) / [ 4(pi)(epsilon naught)(delta x) ] 3. The attempt at a solution 1/[4(pi)(epsilon naught)] = constant = 8.9876x10^6 The Bohr radius= 5.29x10^-11 m <--- (is this delta x?) e = 0.511 MeV =5.11x10^5 eV (is this even correct? does 'e' mean the electron charge or mass?) V(x)= [[-(0.511)^2] . (9.9876x10^6) ] / 5.29x10^-11 =4.436x10^28 As you can see I have many doubts. Hope any of you physics genius can help!