Suppose the conducting spherical shell in the figure below carries a charge of 2.60 nC and that a charge of -2.20 nC is at the center of the sphere. If a = 1.60 mand b = 2.40 m, find the electric field at the following.
(a) r = 1.50 m
(b) r = 2.20 m
(c) r = 2.50 m
(d) What is the charge distribution on the sphere?