1. The problem statement, all variables and given/known data Given a cube with equal charges on all corners save one, find the charge on the origin. http://img79.imageshack.us/img79/4968/cubekg7.jpg [Broken] 2. Relevant equations F = kQ1Q2 3. The attempt at a solution My current idea is splitting up the magnitude of all charges on the origin into their X,Y, and Z components. Because all magnitudes are formed with right triangles I can use pythagorean theorem to solve for the components and I get: Q1: +1 in the X Q2: +1 in the Z Q3: +1 in the Y Q4: +1 in the X, Z Q5: +1 in the X, Y Q6: +1 in the Y, Z Q7: +1 in the X, Y, Z So the sum of the magnitudes acting on the origin would be +4 in all directions, and I have a feeling this is wrong.