1. The problem statement, all variables and given/known data A uniformly charged insulating rod of length 10.0 cm is bent into the shape of a semicircle as shown in the figure below. The rod has a total charge of -9.00 µC. Find the electric potential at O, the center of the semicircle. 2. Relevant equations V=keQ/r 3. The attempt at a solution I already found the answer. It is as simple as plugging in the radius and charge into the relevant equation I wrote. However, why? I don't really understand. At first I was thinking that I have to find the electric field or something and integrate using that one formula, but why is it this simple? Is direction completely irrelevant?