For a ring of charge centered about the origin, how would you calculate the charge experienced by a point within the ring of charge but not at the center? So, I know for a ring of charge dE_x = kdq / r^2 = (k*lambda*ds) / r^2 where ds is the arc length. Then what do I integrate over? And does the fact that the point isn't at the center/origin, important? I'm guessing I need to solve that integral, then determine q.