Figure shows a rectangular array of charged particles fixe in place, with distance a = 39.0cm and

Question:

Figure shows a rectangular array of charged particles fixe in place, with distance a = 39.0cm and the charges shown as integer multiples of q1 = 3.40pC and q2 = 6.00pC. With V = 0 at infinity, what is the net electric potential at the rectangle??scenter.