Question

Two identical conducting spheres, fixed in place, attract each other with an electrostatic force of 0.110 N when their center-to-center separation is 69.5 cm. The spheres are then connected by a thin conducting wire. When the wire is removed, the spheres repel each other with an electrostatic force of 0.0505 N. Of the initial charges on the spheres, with a positive net charge, what was (a) the negative charge on one of them and (b) the positive charge on the other? (Assume the negative charge has smaller magnitude.) (a) Number Units (b) Number Units

Answer 1

When two identical conducting spheres are brought together and then separated, each sphere is left with half of the original charge. The negative charge on one sphere is -4 nC and the positive charge on the other sphere is +4 nC.

Step-by-step explanation:

When the two identical conducting spheres are brought together to touch, the total charge on the two spheres spreads out across the whole surface of the touching spheres. When they are moved apart again, each sphere is left with half of the original charge. Before the spheres touch, the total charge is -5 nC + (-3) nC = -8 nC. When they touch, this charge is shared across their whole surface. When they are separated, each sphere is left with half of the original charge, which means one sphere has a charge of -4 nC and the other sphere has a charge of -4 nC. The negative charge on one sphere is -4 nC (-4 nanoCoulombs) and the positive charge on the other sphere is +4 nC (+4 nanoCoulombs).