JEE Main & Advanced Physics Photo Electric Effect, X- Rays & Matter Waves Question Bank Matter Waves

  • question_answer
    The de-Broglie wavelength of a particle moving with a velocity 2.25 ´ 108 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 ´ 108 m/s) [EAMCET (Med.) 2003]

    A)            1/8

    B)            3/8

    C)            5/8

    D)            7/8

    Correct Answer: B

    Solution :

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


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