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

  • question_answer
    The work function of a metal is \[1.6\times {{10}^{-19}}\]J. When the metal surface is illuminated by the light of wavelength  6400 Å, then the maximum kinetic energy of emitted photo-electrons will be (Planck's constant \[h=6.4\times {{10}^{-34}}Js\]) [MP PMT 1989]

    A)            \[14\times {{10}^{-19}}\ J\]   

    B)            \[2.8\times {{10}^{-19}}\ J\]

    C)            \[1.4\times {{10}^{-19}}J\]     

    D)            \[1.4\times {{10}^{-19}}\,eV\]

    Correct Answer: C

    Solution :

                       \[{{K}_{\max }}=\frac{hc}{\lambda }-{{W}_{0}}=\frac{6.4\times {{10}^{-34}}\times 3\times {{10}^{8}}}{6400\times {{10}^{-10}}}-1.6\times {{10}^{-19}}\]                                                               \[=1.4\times {{10}^{-19}}\,J\]


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