Homework Help: Sphere inside a shell.

1. Feb 22, 2010

reising1

A solid sphere of radius a = 3.00 cm is concentric with a spherical conducting shell of inner radius b = 2.00a and outer radius c = 2.40a. The sphere has a net uniform charge q1 = +4.33 fC; the shell has a net charge q2 = –q1.

What is the magnitude of the electric field at a distance r = a/2 from the center of the sphere?

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Well, I thought the answer was 0 because as I know, the electric field inside a conductor is zero, and the sphere is a conductor. So anywhere in the sphere will have zero charge, since all the charge moves to the surface of the sphere. But, the answer is not zero. Why is this? I'm just so entirely confused with when E is zero and when it is not.

Thanks.

2. Feb 23, 2010

ehild

It was not said that the solid sphere was a conductor.

ehild