Question: Q. 3. A small metallic sphere carrying charge $+Q$ is located at the centre of a spherical cavity in a large uncharged metallic spherical shell. Write the charges on the inner and outer surfaces of the shell. Write the expression for the electric field at the point $P_{1} . \quad \mathrm{R}$ [Comptt. Delhi I, II, III 2014]
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Solution:
Ans. Charge on inner surface : $-Q$
Charge on outer surface : $+Q$
Electric field at point $P_{1}$
$$ \begin{equation*} E=\frac{1}{4 \pi \varepsilon_{0}} \cdot \frac{\mathrm{Q}}{r_{1}^{2}} \tag{1} \end{equation*} $$
[CBSE Marking Scheme, 2014]
