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Chhattisgarh PMT Chhattisgarh PMT Solved Paper-2006

  • question_answer
    The maximum wavelength of radiation that can produce photoelectric effect in a certain metal is 200 nm. The maximum kinetic energy acquired by electron due to radiation of wavelength 100 nm will be

    A)  12.4 eV                               

    B)  6.2 eV

    C)  100 eV                                

    D)  200 eV

    Correct Answer: B

    Solution :

    Given,  \[{{\lambda }_{\max }}=200mn=2\times {{10}^{-7}}m.\] \[\therefore \]  Work function                 \[(W)=\frac{hc}{{{\lambda }_{\max }}}=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{2\times {{10}^{-7}}}\]                 \[=9.9\times {{10}^{-19}}J\]                 \[=6.19eV\] Energy of photon of wavelength\[100\text{ }nm\].                 \[E=\frac{hc}{\lambda }=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{1\times {{10}^{-7}}}\]                 \[=19.8\times {{10}^{-19}}J.\]                 \[=12.37eV\] \[\therefore \] Maximum KE of photoelectron \[=E-W\]                                                 \[=12.37-6.19\]                                                 \[=6.18eV\]                                                 \[\approx 6.2eV\]


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