A cylindrical capacitor has two co-axial cylinders of length $20 \,cm$ and radii $2 r$ and $r$. Inner cylinder is given a charge $10 \,\mu C$ and outer cylinder a charge of $-10 \,\mu C$. The potential difference between the two cylinders will be

  • A

    $\frac{0.1 \ln 2}{4 \pi \varepsilon_0} mV$

  • B

    $\frac{\ln 2}{4 \pi \varepsilon_0} mV$

  • C

    $\frac{10 \ln 2}{4 \pi \varepsilon_0} mV$

  • D

    $\frac{0.01 \ln 2}{4 \pi \varepsilon_0} m V$

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