## Conducting hollow sphere

1. The problem statement, all variables and given/known data

Consider a conductor in the shape of a hollow sphere with inner radius A and outer radius B. The sphere has a net positive charge +q.

A negative point charge of value -2q is placed at the center of the sphere (r=0). Determine the electric field in the three regions of space:
i) r < A
ii) A < r < B
iii) r > B

3. The attempt at a solution

Since this is a conductor, I thought part (i) and (ii) both have 0 Electric Field because the charge on the inside of the sphere will move to the surface, since this is a conductor.

But this is wrong. I need some help here.
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 Quote by reising1 1. The problem statement, all variables and given/known data Consider a conductor in the shape of a hollow sphere with inner radius A and outer radius B. The sphere has a net positive charge +q. A negative point charge of value -2q is placed at the center of the sphere (r=0). Determine the electric field in the three regions of space: i) r < A ii) A < r < B iii) r > B 3. The attempt at a solution Since this is a conductor, I thought part (i) and (ii) both have 0 Electric Field because the charge on the inside of the sphere will move to the surface, since this is a conductor. But this is wrong. I need some help here.
There is charge placed in the center of the hollow sphere.
 Yes, but since it is a conductor, would the charge not immediately move to the inner surface, thus giving no charge on the inside of the conductor?

## Conducting hollow sphere

 Quote by reising1 Yes, but since it is a conductor, would the charge not immediately move to the inner surface, thus giving no charge on the inside of the conductor?
we're dealing with electrostatics here - statics as in not moving. But even if you wanted to think of charge as moving, the point charge is placed inside of a conductor - and you've already told me the E-field inside of a conductor is zero. From where would the force to move it come from?
 Okay, I understand. So in terms of electrostatics, the answer to part i would be E = (-2q)/(4pi * epsilon not * r^2) Now how would I approach part (ii)

 Quote by reising1 Okay, I understand. So in terms of electrostatics, the answer to part i would be E = (-2q)/(4pi * epsilon not * r^2) Now how would I approach part (ii)
Well, in part two it asks for the E-field inside of a solid piece of metal. If there were any E-field, a current would flow to transport the charge until the E-field ceased. Therefore, I'd conclude it to be zero. I could be wrong here, however.

 Tags charge, conductor, electric field, hollow, sphere