Question

A small conducting spherical shell with inner radius $a$ and outer radius $b$ is concentric with a larger conducting spherical shell with inner radius $c$ and outer radius $d$ (as shown in Fig). The inner shell has total charge $+2q$ and the outer shell has charge $+4q$. Calculate the electric field in terms of $q$ and the distance $r$ from the common centre of the two shells for:
$a<r<b$.

• A. Zero
• B. $\frac{1}{4\pi {\epsilon }_0}\frac{2q}{r^2}$
• C. $-\frac{1}{4\pi {\epsilon }_0}\frac{6q}{r^2}$
• D. $\frac{1}{4\pi {\epsilon }_0}\frac{q}{r^2}$

Answer 1

The correct option is A Zero

There is no charge inside the surface $a\le r<b$
since there is no charge inside the inner shell, therefore all the charge will be on outside surface and charge enclosed is zero, hence electric field will also be zero