(i) A conductor A with a cavity as shown in Fig. is given a charge Q. Show that the entire charge must appear on the outer surface of the conductor.
(ii) Another conductor B with charge q is inserted into the cavity keeping B insulated from A. Show that the total charge on the outside surface of A is Q + q [Fig.(b)].
(iii) A sensitive instrument is to be shielded from the strong electrostatic fields in its environment. Suggest a possible way.