Q. A charge of +2q is fixed to one corner of a square, while a charge of -1q is fixed to the diagonally opposite corner. Expressed in terms of q, what charge should be fixed to the center of the square, so the potential is zero at each of the two empty corners?
Q. Two identical point charges are at a fixed distance from one another. if one of their charges was double and the other was halved, how would the electric force be affected?