1. The problem statement, all variables and given/known data Four point charges are individually brought from infinity and placed at the corners of a square whose sides are 0.30 m each. Each charge has the identical value + 4.0 mC. What is the electric potential energy of these four charges? 2. Relevant equations V=kq/r (or at least this is the equation I have been attempting to use to solve this) k= 9 x 10^9 Nm^2/C^2 q= 4 x 10^-6 C r= 3.0 m 3. The attempt at a solution [(9x10^9)(4x10^-6)]/.3=1.2X10^5 Since all charges are the same I take that answer multiply by four to get the sum, which gives me 4.8x10^5 V. However, the answer is in V and I need an answer in Joules (J). So I am assuming I am not even using the correct equation to solve for EPE. I'm sure if I could figure out what equation to use to solve for EPE in Joules, I could do the math. My problem is not knowing what equation to use to solve the problem.