The electric field at point P just outside the outer surface of a hollow spherical conductor of inner radius 10 cm and outer radius 20 cm has magnitude 445 N/C and is directed outward. When an unknown point charge Q is introduced into the center of the sphere, the electric field at P is still directed outward but is now 165 N/C.

(a) What is the net charge on and enclosed by the outer spherical surface before Q is introduced?

C

(b) What is charge Q?

C

(c) After Q is introduced, what is the charge on the inner surface of the conductor?

C

(d) What is it on the outer surface?

C