A spherical conducting shell of inner radius $r_1$ and outer radius $r_2$ has a charge Q. A charge q is placed at the centre of the shell. The surface charge density on outer surface of the shell is:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → $\frac{Q+q}{4πr_2^2}$
Given,
The spherical shell has an inner radius $r_1$ and $r_2$
→ Charge Q placed on the shell
→ Charge q placed on the centre
$∴Q_{outer}=Q+q$
Surface charge density, $σ=\frac{Q_{outer}}{Area\,of\,outer\,surface}$
$=\frac{Q+q}{4πr_2^2}$