A small plastic bead of positive charge +q is placed at the center of an uncharged, hollow, thin spherical shell of radius R. Case 1: The shell is made of copper. Case 2: The shell is replaced by an insulating plastic material of the same size, also initially uncharged. After each system reaches equilibrium, which of the following correctly describes the magnitude of the electric field at a point located a distance R/2 from the center?
a) Case 1: zero; Case 2: greater than zero
b) Case 1: greater than zero; Case 2: zero
c) Case 1: greater than zero; Case 2: greater than zero (same magnitude)
d) Case 1: greater than zero; Case 2: greater than zero but smaller than in Case 1