1. The problem statement, all variables and given/known data Three thin (but finite thickness) concentric conducting shells have radii R1 < R2 < R3 and charges -2Q, +Q, and +3Q respectively, where Q is some positive number. What is the charge on the inner surface of the outmost shell? 2. Relevant equations Charge on a conductor is always on outermost surface? 3. The attempt at a solution So therefore the charge on the inner surface of the outermost shell should be zero? I do not know if this is right. So basically the charge of each shell is transferred to the outermost surface of the outermost shell? I am confused. The answer is 0, right? Just out of curiosity then what's the charge on the outer surface of the outermost shell?