試題詳解

56. A conducting sphere is charged up such that the potential on its surface is 100 V (relative to infinity). If the sphere's radius were twice as large, but the charge on the sphere were the same, what would be the potential on the surface relative to infinity?
(A) 25 V
(B) 50 V
(C) 100V
(D) 200 V
(E) 400 V