PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Electric Force Field and Potential · Electric Force Field and Potential
Problem
Two identical, perfectly spherical objects—Sphere C made of copper (a good conductor) and Sphere G made of solid glass (a good insulator)—are hung from long, non-conducting threads so that they are free to move. Each sphere is initially electrically neutral. A large positively charged metal plate is then placed a short distance to the right of both spheres, with the centers of the spheres remaining the same distance from the plate.
(a) For Sphere C, qualitatively describe the distribution of electric charge once electrostatic equilibrium has been reached. In your description, specify regions of positive and negative charge and comment on the electric field inside the sphere.
(b) For Sphere G, describe the resulting distribution of electric charge at the atomic level. Indicate how the polarization of the glass differs from the charge arrangement in the copper sphere.
(c) Compare the magnitude of the electric field inside Sphere C to that inside Sphere G after equilibrium is reached, and justify your answer.
(d) Based on your answers above, determine which sphere experiences the greater net electrostatic force toward the charged plate. Provide a clear explanation that accounts for both the nature of the material and the induced charge distribution.