Conducting spheres doubt

[tanooj]

This is a doubt that's been irritating me for some time. I've got different answers from teachers and students whenever I've asked.

 

I have two hollow charged conducting spheres, A and B. The radius of A is greater than the radius of B and it also has a greater charge than B, let's say +2q (B has +q). If I put B inside A, and connect them with a wire, will charge flow from A to B or from B to A?

 

If charge flows from A to B, until both reach the same potential (which seems right to me), that goes against the thing that says a conductor should have all of its charge on the outer surface.

 

If charge flows from B to A (because all the charge on a conductor should be on the outer surface), then that means its flowing from lower to higher potential, which seems counter-intuitive.

 

Which one is correct? I've got a board exam tomorrow (think A levels) so it would be great if someone helped me out soon.

[Schrödinger's hat]

The arrangement of the spheres is important.

The potential of each charge depends on where all the other charges are, not just the ones in one sphere.

 

So the charges in the inner sphere actually have higher potential until they are on the outside sphere (the region with lowest potential which the charges to get to).

 

The charges will flow until they all reach the lowest potential they can get to, at which point they are as far away from each other as they can get -- on the outside of the sphere.

 

Also please don't double post. If we see one thread we'll likely soon see the other.

Edited March 7, 2011 by Schrödinger's hat

[tanooj]

oh ok makes sense... the charges are trying to get as far away as possible from the other charges. sorry about the double post. i put it in physics first, but then i thought it would more likely be seen in homework help. thanks!