A large block of insulating material carries a uniform positive volume charge density
PHYSICS · Single correct · AP · Physics C: Electricity and Magnetism · Electric Charges Fields and Gauss's Law · Electric Charges Fields and Gauss's Law
Problem
A large block of insulating material carries a uniform positive volume charge density ρ. A spherical cavity is drilled completely inside the block, entirely within the charged region. After the system re-establishes equilibrium, which statement best describes the electric field at points inside the empty cavity?
(a) The field is zero everywhere inside the cavity because the surrounding charge produces complete cancellation.
(b) The field points radially inward toward the center of the cavity and increases in magnitude with distance from that center.
(c) The field is uniform throughout the cavity and has the same magnitude and direction as the field that existed at the cavity’s center before it was drilled.
(d) The field is uniform but directed opposite to the field that existed at the cavity’s center before it was drilled.