College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 30

Two small beads having positive charges q 1 = 3 q and q 2 = q are fixed at the opposite ends of a horizontal insulating rod of length d = 1.50 m. The bead with charge q 1 is at the origin. As shown in Figure P15.60, a third small charged bead is free to slide on the rod. At what position x is the third bead in equilibrium