A metallic spherical shell has an inner radius $R_1$ and outer radius $R_2$. A charge $Q$ is placed at the centre of the spherical cavity. What will be surface charge density on the inner surface

  • A

    $\frac{Q}{{4\pi R_1^2}}$

  • B

    $ - \frac{Q}{{4\pi R_1^2}}$

  • C

    $\frac{Q}{{4\pi R_2^2}}$

  • D

    $ - \frac{Q}{{4\pi R_2^2}}$

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