Roughly sketch the path of each charge if they are released from rest at the same time, and are allowed to move freely. Here is my sketch : The model answer: Please tell me what is wrong with my sketch. Once R moves to the left side, PR and QR will be shorter than PQ. Attractive electric force on P outweighs the repulsive, similarly for Q. Shouldn't P and Q bend towards R instead of away? Consider when P, Q and R are collinear, there should be a net attractive force between P and Q?