Question

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

• A. $ 50\,nC,100\,nC $
• B. $ ~-\text{ }50\,nC,-\text{ }100\,nC $
• C. $ ~50\text{ }nC,\text{ }200\text{ }nC $
• D. $ ~-\text{ }50\,nC,-200\text{ }nC $

Answer 1

Answer: (B)

The charge + 50 nC at the centre induces
$ -\text{ }50\text{ }nC $
on inner surface and
$ +\text{ }50\text{ }nC $ on outer surface of the spherical sheet.
So, charge on the inner surface
$ =-\text{ }50\text{ }nC $
and charge on the outer surface
$ =-150\,nC+50\,nC $
$ =-100\,nC $