NEET Sample Paper NEET Sample Test Paper-50

  • question_answer If electron, proton and He have same energy, then their de Broglie wavelength decreases in order:

    A) \[{{\lambda }_{e}}>{{\lambda }_{p}}>{{\lambda }_{He}}\]    

    B) \[{{\lambda }_{He}}>{{\lambda }_{p}}>{{\lambda }_{e}}\]

    C) \[{{\lambda }_{He}}>{{\lambda }_{e}}>{{\lambda }_{p}}\]    

    D) \[{{\lambda }_{p}}>{{\lambda }_{e}}>{{\lambda }_{He}}\]

    Correct Answer: A

    Solution :

    de-Broglie wavelength, \[\lambda =\frac{h}{\sqrt{2mE}}\] Since, E is the same, Hence  \[\lambda \propto \frac{h}{\sqrt{m}}\] Since, \[{{m}_{He}}>{{m}_{p}}>{{m}_{e}}\] \[\therefore \,\,\,{{\lambda }_{e}}>{{\lambda }_{p}}>{{\lambda }_{He}}\]


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