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KVPY Sample Paper KVPY Stream-SX Model Paper-3

  • question_answer
    The two particles A and B have de-Broglie wavelengths 2 nm and 5 nm respectively. If mass of A is twice the  mass of B, the ratio of kinetic energies of A and B would be -

    A) 5 : 1                             

    B) 25 : 4

    C) 20 : 1               

    D) 8 : 4

    Correct Answer: B

    Solution :

    [B] \[\frac{{{\lambda }_{B}}}{{{\lambda }_{A}}}=\sqrt{\frac{{{m}_{A}}{{E}_{A}}}{{{m}_{B}}{{E}_{B}}}}\] \[\frac{{{E}_{A}}}{{{E}_{A}}}={{\left( \frac{{{\lambda }_{B}}}{{{\lambda }_{A}}} \right)}^{2}}.\frac{{{m}_{B}}}{{{m}_{A}}}\]\[={{\left( \frac{5}{2} \right)}^{2}}.\frac{1}{2}=\frac{25}{4}\]


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