Four charges +q, +q, -q, -q are placed respectively at the corners A, B, C, D of a square of side a, the potential and Field at the center of the square are:-A.) zero, 4q/a^2 B.) zero, 4sqrt(2q)/a^2 C.) 4sqrt(2q)/a, 4q/a^2 D.) 4sqrt(2q)/a, 4sqrt(2q)/a^2 Please answer with detail explaination
