(a) If both q1 and q2 are positive, the electrostatic force between these will be repulsive. However, if one of these charges is positive and is greater than the other negative charge, the electrostatic force between them will be attractive. Thus, the nature of force between them can be repulsive or attractive.
(b) If both q1 and q2 are –ve, the force between these will be repulsive. However, if one of them is –ve and it is greater in magnitude than the second +ve charge, the force between them will be attractive. Thus, the nature of force between them can be repulsive or attractive.
