Question

A solid conducting sphere of radius $a$ has a net positive charge $2Q$. A conducting spherical shell of inner radius $b$ and outer radius $c$ is concentric with the solid sphere and has a net charge $-Q$. The surface charge density on the inner and outer surfaces of the spherical shell will be

• A. $\frac{2Q}{4\pi b^2},\frac{Q}{4\pi c^2}$
• B. $-\frac{2Q}{4\pi b^2},\frac{Q}{4\pi c^2}$
• C. $0,\frac{Q}{4\pi c^2}$
• D. $Noneofthese$

Answer 1

The correct option is B $-\frac{2Q}{4\pi b^2},\frac{Q}{4\pi c^2}$

Surface charge density $\left(\sigma \right)=\frac{charge}{Surfacearea}$
${\sigma }_{inner}=\frac{-2Q}{4\pi b^2};{\sigma }_{outer}=\frac{Q}{4\pi c^2}$