BCECE Medical BCECE Medical Solved Papers-2013

  • question_answer
    A photon and an electron possess same de-Broglie wavelength given that C = speed of light and \[\upsilon =\] space of electron, which of the following relation is correct? (here, \[{{E}_{e}}=K.\,E\] of electron, \[{{E}_{Ph}}=K.\,E\] of photon, \[{{P}_{e}}=\] momentum of electron, \[{{P}_{ph}}=\]momentum of photon)

    A)  \[\frac{{{P}_{e}}}{{{P}_{Pn}}}=\frac{C}{2v}\]

    B)  \[\frac{{{E}_{e}}}{{{E}_{Pn}}}=\frac{C}{2v}\]

    C)  \[\frac{{{E}_{ph}}}{{{E}_{e}}}=\frac{2C}{v}\]

    D)  \[\frac{{{P}_{e}}}{{{P}_{ph}}}=\frac{2C}{v}\]

    Correct Answer: C

    Solution :

    We have , \[{{\lambda }_{Ph}}=\frac{h}{{{P}_{ph}}}\] and \[{{\lambda }_{e}}=\frac{h}{{{P}_{e}}}\] Given, \[{{\lambda }_{Ph}}={{\lambda }_{e}}\] \[\therefore \] We get, \[{{P}_{Ph}}={{P}_{e}}\] \[\frac{h}{{{\lambda }_{Ph}}}=mv\] \[\therefore \] \[\frac{hc}{{{\lambda }_{Ph}}}=mcv=\frac{1}{2}\left( \frac{2c}{v} \right)\] or \[\frac{{{E}_{Ph}}}{{{E}_{e}}}=\frac{2c}{v}\]


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