# Electric Potentials

1. Feb 24, 2005

### brichugh

A hollow cylindrical shell of length L and radius R has charge Q uniformly distributed along its length. What is the electric potential at the center of the cylinder?

I use eta = Q/A = Q/2piRL

dq = (eta)*dA = Q/(2piRL)*2piRdL

dV = 1 / 4 pi epsilon 0 * dq/r where r = sqrt(L^2+R^2)

V = Q/(4*pi*epsilon_0)*int(dL/(sqrt(L^2+R^2)))

This seems to be incorrect can someone tell me where I have gone wrong?

2. Feb 24, 2005

### Gamma

You are missing an H = height of the cylinder in the denominator of the equation.

Also limits of the integral (-h/2 -> h/2) if your referance point is the middle of the cylinder.

Last edited: Feb 24, 2005