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

  • A
    $t = \frac{\pi }{2}\sqrt {\frac{{4\pi { \in _0}m{R^3}}}{{qQ}}} $
  • B
    $t = \frac{\pi }{2}\sqrt {\frac{{2\pi { \in _0}m{R^3}}}{{qQ}}} $
  • C
    $t = \frac{\pi }{4}\sqrt {\frac{{2\pi { \in _0}m{R^3}}}{{qQ}}} $
  • D
    $t = \frac{\pi }{4}\sqrt {\frac{{4\pi { \in _0}m{R^3}}}{{qQ}}} $

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