I have a ring, radius a, with a charge distributed evenly around it. Using a gaussian cylinder of radius r, r<<a (or otherwise). Find the electric field at at small distance r away from the centre of the ring, r is in the plane of the ring.
I know that the answer is
[tex]\int E\cdot ds = Q/\epsilon_0[/tex]
The Attempt at a Solution
I can't get started since I find that the charge enclosed is 0