RAJASTHAN ­ PET Rajasthan PET Solved Paper-2001

  • question_answer
    If the threshold frequency of sodium metal is 6800 A, then work function will be

    A)  1.8 eV           

    B)  2.5 eV

    C)  2.1 eV           

    D)  1.4 eV

    Correct Answer: A

    Solution :

     \[W=\frac{hc}{\lambda }=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{6800\times {{10}^{-10}}}\] \[=2.9\times {{10}^{-19}}J\] \[=\frac{2.9\times {{10}^{-19}}}{1.6\times {{10}^{-19}}}=1.8\,eV\]


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