A total amount of charge Q is uniformly distributed along a thin semicircle of radius R. Show that the electric field at a point P at the center of the circle is FR' . Use a Riemann sum. (Hint: Recall that S = R9, so 335 7-3 R36, or d3 = Rda. This problem is much easier if we use 3 as our variable of integration. Also note that if you get a really hard integral, you are either making the problem harder that it has to be, or you are doing it wrong.)