1. The problem statement, all variables and given/known data Two small beads having positive charges 3q and q are fixed at the opposite ends of a horizontal, insulating rod, extending from the origin to the point x=d. A third small charged bead is free to slide on the rod. At what position is the third bead in equilibrium? What type of charge makes makes it stable? 2. Relevant equations F= Ke(q1q2)/r^2 3. The attempt at a solution I got the answer right, but for the second part of the question, the answer booklet said that a positive charge makes this particular situation stable, but I do not get why a negative charge can't also make the situation stable?