Consider two concentric conducting spheres (Figure). The outer sphere is hollow and initially has a charge ?7Q deposited on it. The inner sphere is solid and has a charge +2Q on it.

(a) How is the charge distributed on the outer sphere? That is, how much charge is on the outer surface and ho much charge is on the inner surface?

(b) Suppose a wire is connected between the inner and outer spheres. After electrostatic equilibrium is established, how much total charge is on the outside sphere? How much charge is on the outer surface of the outside sphere and how much is on the inner surface? Does the electric field at the surface of the inside sphere change when the wire is connected? If so, how?

(c) Suppose we return to the original conditions in (a), with +2Q?on the inner sphere and ?7Q?on the outer. We now connect the outer sphere to ground with a wire and then disconnect it. How much total charge will be on the outer sphere? How much charge will be on the inner surface of the outer sphere and how much will be on the outer surface?

-7Q +2Q