Question

A charge $q$ is placed at the centre of a conducting spherical shell of radius $R,$ which is given a charge $Q.$ An external charge $Q^{\prime }$ is also present at distance $R^{\prime }(R^{\prime }>R)$ from $q^{\prime }.$ Then the resultant field will be best represented for region $r<R$ is-
[where $r$ is the distance of the point from $q$]

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

According to electrostatic shielding, inside the cavity, there will not be any electrostatic effect due to any external charges.

Using Gauss's law, due to pint charge $q$ at centre. considering a Gaussian surface of radius $r,(r<R)$

$\varphi =\frac{q_{\text{enclosed}}}{{\epsilon }_0}=\int E.dA$

$\Rightarrow E=\frac{q}{4\pi {\epsilon }_0{r}^2}$

$\Rightarrow E\propto \frac{1}{r^2}$



At $r=0\to E=\infty$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(A\right)$ is the correct answer.