1. The problem statement, all variables and given/known data Im trying to calculate the electric potential created by a circular rod of charge Q and radius R at a random point (not only on the rod's axis). The rod can be considered very thin. 2. Relevant equations 3. The attempt at a solution V = k \int dq/r My problem is how to express r in a better way. I know i have to use cylindrical coordnates (r,z) but how can i express the distance from the charge element dq when the point P is not on the rods axis?