WB JEE Medical WB JEE Medical Solved Paper-2012

  • question_answer
    The de-Broglie wavelength of an electron moving with a velocity c/2 (c = velocity of light in vacuum) is equal to the wavelength of a photon. The ratio of the kinetic energies of electron and photon is

    A)  1:4   

    B)  1:2 

    C)  1:1   

    D)  2:1

    Correct Answer: B

    Solution :

     de-Broglie wavelength \[\lambda =\frac{h}{mv}\] Here, \[{{\lambda }_{e}}=\frac{h}{{{m}_{e}}\frac{c}{2}}\]and \[{{\lambda }_{p}}=\frac{h}{{{m}_{p}}c}\] Given, \[{{\lambda }_{e}}={{\lambda }_{p}}\] So, \[\frac{h}{{{m}_{e}}\frac{c}{2}}=\frac{h}{{{m}_{p}}c}\] \[\frac{{{m}_{e}}}{{{m}_{p}}}=2\] Ratio of KE \[\frac{{{K}_{e}}}{{{K}_{p}}}=\frac{\frac{1}{2}{{m}_{e}}v_{e}^{2}}{\frac{1}{2}{{m}_{p}}v_{p}^{2}}\] \[\frac{{{K}_{e}}}{{{K}_{p}}}=\frac{1}{2}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner