PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Electric Force Field and Potential · Electric Force Field and Potential
Problem
Two identical conducting spheres, X and Y, are mounted on insulating stands and placed several centimeters apart so that no discharge can jump the gap. Initially sphere X carries a charge of −1.20×10−8C and sphere Y is neutral. A metal rod momentarily connects the two spheres, allowing charge to redistribute. The connecting rod is then removed.
(a) Determine the final net charge on each sphere after they are disconnected.
(b) Calculate the number of electrons that moved through the connecting rod during the brief contact.
(c) Explain, without additional calculations, why the spheres end with equal charges even though only one sphere was initially charged.
(d) If instead the spheres had been of unequal radii (while still identical materials), qualitatively predict how the final charges would compare, and justify your reasoning based on principles of electrostatics.