MGIMS WARDHA MGIMS WARDHA Solved Paper-2005

  • question_answer
    A light of wavelength 5000Å falls on a     sensitive plate with photo electric work                function 1.90 eV. Kinetic energy of the         emitted photo electrons will be : Given, \[h=6.62\times {{10}^{-34}}\]Joule-second)

    A) 0.1 eV                                  

    B) 2 eV,

    C) 0.581 eV                              

    D) 1.581 eV

    Correct Answer: C

    Solution :

    Energy of incident radiation \[E=\frac{hc}{\lambda }\] \[=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{5000\times {{10}^{-10}}}J\] \[=\frac{6.6\times 3\times {{10}^{-19}}}{5}=3\times 96\times {{10}^{-19}}J\] \[=\frac{3.96\times {{10}^{-19}}}{1.6\times {{10}^{-19}}}=2.48\,eV\] \[\therefore \]K.E. of emitted photo electrons \[=E-W\] \[=2.48-1.90=0.58\text{ }eV\]


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