1. The problem statement, all variables and given/known data Consider two concentric spherical conducting shell. The inner sphere has radius r1, potential V1, while the outer sphere has radius r2, potential V2. Find the potential at the center of these two sphere, at r0=(r1+r2)/2. 2. The attempt at a solution I tried to use method of images, by modelling there to be a charge q1 at the center of the inner sphere and q2 at the center of the outer sphere. Since both sphere are concentric, q1 and q2 are at the same location. So I attempt to add up q1 and q2 (which I now know is wrong), and then find the potential at r0. My answer is double the correct answer.