The problem statement, all variables and given/known data I two concentric metalical spheres r1 =/= r2. What to do to have: a) potential energy = 0 and electric charge =/= 0 b) potential energy =/= 0 and electric charge =0. In eighter one of the spheres. Relevant equations Gauss law. 3. The attempt at a solution a) If I charge the outside sphere, I will have potential energy = 0 on it and electric charge =/= 0. b) I tought If I charge the one inside with Q, I will have a potential =/= 0 on the bigger sphere and 0 charge. Is this correct? The problem does not give correct answer.