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JEE Main & Advanced Physics Nuclear Physics And Radioactivity Question Bank Critical Thinking

  • question_answer
    The rest mass of an electron as well as that of positron is 0.51 MeV. When an electron and positron are annihilate, they produce gamma-rays of wavelength(s)                    [UPSEAT 2002]

    A)            0.012 Å                                   

    B)            0.024 Å

    C)            0.012 Å to ¥                         

    D)            0.024 Å to ¥

    Correct Answer: A

    Solution :

               Since electron and positron annihilate                    \[\lambda =\frac{hc}{{{E}_{Total}}}=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{(0.51+0.51)\times {{10}^{6}}\times 1.6\times {{10}^{-19}}}\]                    \[=1.21\times {{10}^{-12}}m=0.012{\AA}\].


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