A thin plastic rod 15 cm long carries 4.2 nC distributed uniformly over its length.
(a) If the rod is bent into a ring, find the potential at its center.
(b) If the rod is bent into a semicircle, find the potential at the center (i.e., at the center of the circle of which the semicircle is part).
V = KQ/r potential at a point.
The Attempt at a Solution
when bending the rod, how to find the distance r.