Consider three identical metal spheres, A, B, and C. Sphere A carries a charge of +7q. Sphere B carries a charge of – 2q. Sphere C carries no net
charge. Spheres A and B are touched together and then separated.
Sphere C is then touched to sphere A, and separated from it. Last, sphere
C is touched to sphere B and separated from it. (a) How much charge
ends up on sphere C? What is the total charge on the three spheres (b)
before they are allowed to touch each other and (c) after they have
touched?