\fA total amount of charge 0 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 n32 . Use a Riemann sum. (Hint: Recall that s = RH, so As R5 RAG, or (L? = Rd This problem is much easier if we use 9 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.)