1. The problem statement, all variables and given/known data A solid spherical conductor carries a charge Q. It is surrounded by a concentric uncharged spherical shell. The potential difference between the surface of solid sphere and the shell is V. If a charge of -3Q is given to the shell. Then the new potential difference between the above two points will be - 3. The attempt at a solution In my view, as both the shell share their center and we know that in conductors we assume that charges are concentrated at the center so charge given to any of the shell increase or decrease the potential of both the shell by the same amount and so there will be no change in potential difference. But I want verification from some knowledgeable or learned person.