Question -
Answer -
(a) Charge placed at the centre of a shell is +q.Hence, a charge of magnitude −q will be induced to the innersurface of the shell. Therefore, total charge on the inner surface of the shellis −q.
Surface charge density at the inner surface of the shellis given by the relation,
A charge of +q is induced onthe outer surface of the shell. A charge of magnitude Q isplaced on the outer surface of the shell. Therefore, total charge on the outersurface of the shell is Q + q. Surface chargedensity at the outer surface of the shell,
(b) Yes
The electric field intensity inside a cavityis zero, even if the shell is not spherical and has any irregular shape. Take aclosed loop such that a part of it is inside the cavity along a field linewhile the rest is inside the conductor. Net work done by the field in carryinga test charge over a closed loop is zero because the field inside the conductoris zero. Hence, electric field is zero, whatever is the shape.