A uniformly-charged ring (total charge , where is positive) of radius and negligible thickness is situated in the x-y plane with its center at (x,y) = (0,0). Find an expression for the electric field at the point z = ℎ. Take the limit of your expression as ℎ≫ to show that the electric field of the ring looks like that of a point charge as ℎ grows very large.