Two pith balls having charge `3_(q)` and `2_(q)` are placed at distance of a from each other. For what value of charge transferred from `1 ^(st)` ball to `2^(nd)` ball, force between balls becomes maximum?

Two point charges A and B, having charges +Q and -Q respectively, are placed at certain distance apart and force acting between them is F, if 25% charge of A is transferred to B, then force between the charges becomes:

A total charge Q is broken in two parts Q_(1) and Q_(2) and they are placed at a distance R from each other. The maximum force of repulsion between them will occur, when

Two small balls carrying charges +9 mu C" and -4 mu C attract each other with a force "F" .If a charge of -5 mu C is added to each one of them,then the force between the balls would become

Two identical metals balls with charges +2Q and -Q are separated by some distance and exert a force F on each other . They are joined by a conducting wire , which is then removed. The force between them will now be

Two identical balls having like charges and placed at a certain distance apart repel each other with a certain force. They are brought in contact and then moved apart to a distance equal to half their initial separation. The force of repulsion between them increases 4.5 times in comparision with the initial value. The ratio of the initial charges of the balls is

On a horizontal table, there is a smooth circular groove of mean radius R. The walls of the groove are non conducting. Two metal balls (each having mass m and radius r) are placed inside the groove with their centers R apart. The balls just fit inside the groove. The two balls are given charge + 3q and – q and released from state of rest. Ignore the non-uniformity in charge distribution as the balls come close together and collide. The collision is elastic. Find maximum speed acquired by each ball after they collide for the first time.

Two point electric charges of values q and 2q are kept at a distance d apart from each other in air. A third charge Q is to be kept along the same line in such a way that the net force acting on q and 2q is zero.Find the location of the third charge from charge q.

Two identical small conducting balls have positive charges q_1 and q_2 respectively. The force between the balls when they are placed at a separation is F. The balls are brought together so that they touch and then put back in their original positions. Prove that the force between the balls now, cannot be less than F.