JEE Main & Advanced Sample Paper JEE Main Sample Paper-19

  • question_answer A photon materializes into an electron-positron pair. The kinetic energy of the electron is found to be \[0.19\text{ }MeV\]. What was the energy of the photon?

    A)  \[0.38\text{ }MeV\]                   

    B)  \[0.70\text{ }MeV\]

    C)  \[1.40\text{ }MeV\]                   

    D)  None

    Correct Answer: C

    Solution :

     Conservation of Energy, \[Photon\to {{e}^{+}}+{{e}^{-}}+energy\] \[{{E}_{P}}={{E}_{r{{e}^{+}}}}+{{E}_{r{{e}^{-}}}}+K.E.\] of both \[{{e}^{-}}+{{e}^{+}}\] We know that  rest mass energy of \[{{e}^{+}}+{{e}^{-}}\]is.\[5\text{ }MeV\] Hence \[{{E}_{p}}=.5+.5+.19\times 2=1.40\,MeV\]

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