A solid insulating sphere of radius is uniformly charged with total charge
PHYSICS · Multi-part · AP · Physics C: Electricity and Magnetism · Conductors and Capacitors · Conductors and Capacitors
Problem
A solid insulating sphere of radius R is uniformly charged with total charge +Q. A narrow, spherical cavity of radius 3R is drilled completely inside the sphere so that the cavity’s center is located a distance 2R from the center of the original sphere, but no charge is removed from the remaining material. In a separate scenario, an identically shaped solid conductor—also of radius R—has the same cavity drilled in the same off-center position, and the conductor is given a total charge +Q.\
Assume both objects reach electrostatic equilibrium.
(1) Part 1: (a) For the insulating sphere, describe qualitatively the direction and relative magnitude (stronger, weaker, or zero) of the electric field at the geometric center of the cavity. Explain the physical reasoning that leads to your prediction.
(2) Part 2: (b) For the conducting sphere, describe qualitatively the electric field at every point within the cavity. Explain how the conductor’s charge distribution produces this result.
(3) Part 3: (c) Compare and contrast your answers to parts (a) and (b). Identify the specific physical properties of insulators and conductors that account for any differences in the field inside the cavity.