NEET Physics Atomic Physics NEET PYQ-Atomic Physics

  • question_answer
    An electron of mass m and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is :          [NEET - 2016]

    A)  \[\frac{1}{c}{{\left( \frac{E}{2m} \right)}^{\frac{1}{2}}}\]       

    B)              \[{{\left( \frac{E}{2m} \right)}^{\frac{1}{2}}}\]

    C)  \[c{{\left( 2mE \right)}^{\frac{1}{2}}}\]

    D)       \[\frac{1}{xc}{{\left( \frac{2m}{E} \right)}^{\frac{1}{2}}}\] (c being velocity of light)

    Correct Answer: A

    Solution :

    [a] For electron \[\,{{\lambda }_{e}}=\frac{h}{\sqrt{2mE}}\]
                For Photon\[E=pc\]
    \[\Rightarrow \]   \[{{\lambda }_{Ph}}=\frac{hc}{E}\]
    \[\Rightarrow \]   \[\frac{{{\lambda }_{e}}}{{{\lambda }_{Ph}}}=\frac{h}{\sqrt{2mE}}\times \frac{E}{hc}={{\left( \frac{E}{2m} \right)}^{1/2}}\frac{1}{c}\]


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