Shown in the figure are two point charges +Q and -Q inside the cavity of a spherical shell. The charges are kept near the surface of the cavity on opposite sides of the centre of the shell. If 1 is the surface charge on the inner surface and Q1 net charge on it and 2 the surface charge on the outer surface and Q2 net charge on it then

(A) \begin{array}{l} {\sigma _1}\, \ne \,0,\,\,{Q_1}\, = \,0\\ {\sigma _2}\, = \,0,\,\,{Q_2}\, = \,0 \end{array}

(B) \begin{array}{l} {\sigma _1}\, \ne \,0,\,\,{Q_1}\, = \,0\\ {\sigma _2}\, \ne \,0,\,\,{Q_2}\, = \,0 \end{array}

(D) \begin{array}{l} {\sigma _1}\, \ne \,0,\,\,{Q_1}\, \ne \,0\\ {\sigma _2}\, \ne \,0,\,\,{Q_2}\, \ne \,0 \end{array}

JEE Mains · Physics · STD 12 - Electric charges and fields

Shown in the figure are two point charges \(+Q\) and \(-Q\) inside the cavity of a spherical shell. The charges are kept near the surface of the cavity on opposite sides of the centre of the shell. If \(\sigma _1\) is the surface charge on the inner surface and \(Q_1\) net charge on it and \(\sigma _2\) the surface charge on the outer surface and \(Q_2\) net charge on it then

Pick an option to check your answer.

Verified Solution

Correct Answer

(C) \(\begin{array}{l}
{\sigma _1}\, = \,0,\,\,{Q_1}\, = \,0\\
{\sigma _2}\, = \,0,\,\,{Q_2}\, = \,0
\end{array}\)

Detailed explanation

Inside the cavity net charge is zero.

\(\therefore \quad Q_{1}=0\) and \(\sigma_{1}=0\)

There is no effect of point charges \(+Q\)

\(Q\) and induced charge on inner surface on the outer surface.

\(\therefore \quad Q_{2}=0\) and \(\sigma_{2}=0\)

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