Energy of negative charge near conducting shell · CAP 2004 #Q24
Physics · electromagnetism
Problem
You are moving a negative charge q<0 at a small constant speed away from a conducting spherical shell on which resides a negative charge Q<0. The electrostatic field of Q is E. Let U be the total energy of q, Wa the work done by the force Fa you exert on q, and WE the work done by the electrostatic force FE on q. Then, as q is being moved,
(a) Wa=−WE, and therefore U remains constant;
(b) Fa=−FE, and therefore U remains constant;
(c) U increases;
(d) U decreases.