1. The problem statement, all variables and given/known data Find the potential at points a and b in the diagram for charges Q1 = +1.60 nC and Q2 = -1.60 nC. I know b is 0 2. Relevant equations V = kQ/r 3. The attempt at a solution I tried this using the equation and got 8.99e9 * [( +1.60e-6 / .05) + ( -1.60e-6 / .15 ) ] = 191700 V but this isn't right any suggestions??