A solid metal ball of radius 1.1 cm is located near a hollow plastic ball of radius 2.2 cm bearing a uniformly distributed charge of -5 nC on its outer surface. The distance between the centers of the balls is 8 cm.

(a) Click the edge of the metal ball that has an excess of positive charges.
(b) What is the electric field at the center of the metal ball due just to the charges on its surface? Assume the +x axis is the right, the +y axis is up and the +z axis is out.
< x, 0,0> N/C