RAJASTHAN PMT Rajasthan - PMT Solved Paper-2006

  • question_answer
    If wavelength \[\lambda =5400\overset{\text{o}}{\mathop{\text{A}}}\,\] is threshold value for a certain metal, then its work function would be:

    A)  2.3 eV                                 

    B)         0.025 eV

    C)         10 eV                                   

    D)         0.23 eV

    Correct Answer: A

    Solution :

    \[E=\frac{hc}{\lambda }J=\frac{hc}{\lambda \times 1.6\times {{10}^{-19}}}eV\] \[\Rightarrow \]\[E=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{5400\times {{10}^{-10}}\times 1.6\times {{10}^{-19}}}eV\] \[\Rightarrow \]\[E=2.3\,\,eV\]


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