$A$ and $C$ are concentric conducting spherical shells of radius $a$ and $c$ respectively. $A$ is surrounded by a concentric dielectric radius $a$ , outer radius $b$ and dielectric constant $k$ . If sphere $A$ be given a charges $Q$ , the potential at the outer surface of the dielectric is 

822-276

  • A

    $\frac{Q}{{4\pi {\varepsilon _0}kb}}$

  • B

    $\frac{Q}{{4\pi {\varepsilon _0}}}\left( {\frac{1}{a} + \frac{1}{{k\left( {b - a} \right)}}} \right)$

  • C

    $\frac{Q}{{4\pi {\varepsilon _0}b}}$

  • D

    None of these

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