Consider a solid conducting sphere with radius a and charge Q1 and a concentric conducting spherical shell with inner radius b > a , outer radius c and a net charge Q 2 .

Denote the charge on the inner surface of the shell by Q'2 and on the outer surface by Q??2
1. find the charge Q''2
2. Find the magnitude of the electric field at point P (||EP|| ? EP) , where the distance from
P to the center is (a+b)/2
3.Find the potential VP at point P. Assume the potential at r=?is zero