question_answer 28)

(a) A conductor A with a cavity as shown in figure (a) is given a charge Q. Show that the entire charge must appear on the outer surfaceof the conductor.                 (b) 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 [Figure (b)].                 (c) A sensitive instrument is to be shielded from the strong electrostatic fields in its environment Suggest a possible way.  

Answer:

Select a Gaussian surface inside the conductor but very, the surface of the conductor                 (a) There is no electric field conductor so electric flue Gaussian surface is zero or in words net charge inside Gaussian surface is zero. Then it can be said that the charge lies outside the Gaussian surface i.e. on the outer surface of the conductor.                 (b) Charge inside the cavity will induce a charge on the inner side of cavity and thus will appear on outer surface. Thus total charge will be .                 (c) The instrument should be enclosed in a metallic shell so that the effect of electrostatic field is cancelled out.