Electrical potential of charged sphere

kasse

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

Two charged metal spheres are connected by a wire. Sphere A is larger than sphere B. The magnitude of the electrical potential of A...

a) is greater than at the surface of sphere B
b) is less than at the surface of sphere B
c) is the same as that at the surface of sphere B

3. The attempt at a solution

Electric potential: V = q/(4*pi*e₀*r)

Since the spheres are connected by a wire, their charge will be equal. We regard the charges at the spheres as point charges in the centers of the spheres. Then the magnitude of the electrical potential of A is less than at the surface of B since r_A > r_B

Why am I wrong?

Dick

I don't know how to say this without giving the whole thing away, but do you really think that if I connect a huge sphere with a lot of charge (like the earth) to a small sphere (like a steel marble) that they will they will split the charge equally? Something will be equal between the two spheres, but it won't be charge.

kasse

So c) is the correct answer. How can this be explained?

michalll

The potential on the surface must be constant, otherwise there would exist tangential field E that moves the charges until equipotential is reached.