JEE Main & Advanced Sample Paper JEE Main Sample Paper-46

  • question_answer
    The de-Broglie wavelength of a particle moving with a velocity \[2.25\times {{10}^{8}}\] m/s is equal to the wavelength of photon. The ratio of kinetic energy of the particle to the energy of the photon is (velocity of light is \[3\times {{10}^{8}}\] m/s)

    A)  \[\frac{1}{8}\]                                   

    B)  \[\frac{3}{8}\]

    C)  \[\frac{5}{8}\]                                   

    D)  \[\frac{7}{8}\]

    Correct Answer: B

    Solution :

     \[{{K}_{particle}}=\frac{1}{2}m{{v}^{2}},\] also \[\lambda =\frac{h}{mv}\] \[\Rightarrow \]            \[{{K}_{particle}}=\frac{1}{2}\,\left( \frac{h}{v\,\lambda } \right)\cdot \,{{v}^{2}}=\frac{vh}{2\lambda }\] \[{{K}_{photon}}=\frac{hc}{\lambda }\] \[\therefore \]    \[\frac{{{K}_{particle}}}{{{K}_{photon}}}=\frac{v}{2c}=\frac{2.25\times {{10}^{8}}}{2\times 3\times {{10}^{8}}}=\frac{3}{8}\]


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