JEE Main & Advanced Physics Nuclear Physics And Radioactivity JEE PYQ-Nuclear Physics

  • question_answer
    Both the nucleus and the atom of some element are in their respective first excited states. They get de-excited by emitting photons of wavelengths\[{{\lambda }_{N}},{{\lambda }_{A}}\]respectively. The ratio \[\frac{\lambda N}{\lambda A}\] is closest to [JEE Main Online 16-4-2018]

    A) \[{{10}^{-6}}\]

    B) 10 

    C) \[{{10}^{-1}}\]

    D) \[{{10}^{-10}}\]

    Correct Answer: A

    Solution :

    [a] \[\frac{{{E}_{A}}}{{{E}_{B}}}=\frac{\frac{hc}{{{\lambda }_{A}}}}{\frac{hc}{{{\lambda }_{N}}}}\]
    So, \[\frac{{{E}_{A}}}{{{E}_{N}}}=\frac{{{\lambda }_{N}}}{{{\lambda }_{A}}}\]
    As order of\[{{E}_{A}}=ev\]
    and order of \[{{E}_{N}}=Mev\]
    \[\therefore \] \[\frac{{{\lambda }_{N}}}{{{\lambda }_{A}}}=\frac{1ev}{1Mev}=\frac{1}{{{10}^{6}}}={{10}^{-6}}\]
    So option A is correct Answer


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