# Electric potential of a solid copper sphere

bfusco

## Homework Statement

An isolated solid copper sphere of radius .12m has a positive charge of 6.4x10^-9 C.
i) calculate the electric potential at a point .10 m from the center of the sphere.
ii)calculate the electric potential at a point .24 m from the center of the sphere.

## The Attempt at a Solution

i) originally i thought the answer was 0 because since the sphere is copper it is conducting, so all the charge is on the surface of the sphere so at a distance .1 m (not reaching the surface) i assumed the potential was 0. i now know that this is incorrect. if someone could explain that to me i would appreciate it. is it because the electric potential doesn't work exactly like Gauss' law in that where the charge is matters.

ii)i used the equation V=kQ/R, however instead of using the .24 meters from the center, i used .12 m as R because the charge is at the surface, so a point .12m away from the surface of the sphere is only .12 m away from the charge. its apparently wrong and i don't understand why.