1. The problem statement, all variables and given/known data This is a http://session.masteringphysics.com/problemAsset/1003223/45/14677_a.jpg" [Broken] of the problem -I know that the direction of the electric field at any point on the z-axis is parallel to the z-axis E = k*q/r^2 http://session.masteringphysics.com/problemAsset/1003223/45/1003223B2.jpg" [Broken] dE = k* dq/(a^2+z^2) dEz = (z/(sqrt(a^2+z^2)) *dE 3. The attempt at a solution So, I need to find the magnitude of the electric field along the positive z axis. Basically, everything up there was work from previous parts of the problem. Now, I think I just need to put the last two expressions together in order to integrate around the ring (I think with respect to q), but I'm not sure. I need a little help on this last step.