Question

If a charge $-150\, nC$ is given to a concentric spherical shell and a charge $+50\, hC$ is placed at its centre then the charge on inner and outer surface of the shell is

• A. -50 nC ,-100 nC
• B. +50 nC ,-200 nC
• C. -50 nC ,-200 nC
• D. 50 nC , 100 nC

Answer 1

Answer: (A)

Whenever a charge $(+50 \,nC )$ is kept inside a hollow metallic spherical shell, it induces an equal and opposite charge on the inner surface and an equal and same type of charge on the outer surface.
$\therefore $ Inside, induced charge is $-50 \,nC$ and outside, $+50 \,n C$.
As $-150 \,nC$ charge is already present outside, hence net charge on outer surface is $-100 \,nC$.