PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Electric Force Field and Potential · Electric Force Field and Potential
Problem
Two identical, initially neutral, conducting spheres X and Y are mounted on insulating stands so that they are just touching. A negatively charged rod is brought near sphere X but never touches either sphere. While the rod remains in place, the spheres are gently pulled apart to a distance large enough that no further charge can flow between them. The rod is then removed.
Assume no charges are added to or removed from the two–sphere system at any time during the procedure.
(a) Describe qualitatively how the free charges redistribute themselves on the two spheres while the rod is present and the spheres are still touching.
(b) Explain why the net charge of the two–sphere system remains zero from the moment the rod is brought nearby until after the spheres are separated and the rod is removed.
(c) After the rod is removed and the spheres are far apart, state the sign of the net charge on each sphere and explain your reasoning in terms of charge conservation and the separation step.