Question

A thin glass rod is bent into a semicircle of radius r. A charge +q is uniformly distributed along the upper half, and a charge of -q is distributed along the lower half, as shown in Fig. 23-34b. Find the magnitude and direction of the electric field E at P, the center of the semicircle.


(a) The magnitude of the electric field at P is:

q / (2*0*r2)
q*r2 / (2*0)
q*r2 / (*0)
-q*r2 / (2*0)
q / (2**0*r2)