$A$ charged particle with charge $q$ and mass $m$ starts with an initial kinetic energy $K$ at the centre of a uniformly charged spherical region of total charge $Q$ and radius $R$. Charges $q$ and $Q$ have opposite signs. The spherically charged region is not free to move and kinetic energy $K$ is just sufficient for the charged particle to reach the boundary of the spherical charge. How much time does it take the particle to reach the boundary of the region?

  • A
    $\pi \sqrt {\frac{{4\pi {\varepsilon _0}m{R^3}}}{{qQ}}} $
  • B
    $\frac{\pi }{2}\sqrt {\frac{{4\pi {\varepsilon _0}m{R^3}}}{{qQ}}} $
  • C
    $\frac{\pi }{4}\sqrt {\frac{{4\pi {\varepsilon _0}m{R^3}}}{{qQ}}} $
  • D
    None of these

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