JCECE Medical JCECE Medical Solved Paper-2002

  • question_answer
    Work function of photoelectric metal is 3.13 eV. Threshold frequency is:

    A)  \[4\times {{10}^{11}}\,Hz\]

    B) \[5\times {{10}^{14}}\,Hz\]

    C)  \[8\times {{10}^{15}}\,Hz\]

    D) \[8\times {{10}^{10}}\,Hz\]

    Correct Answer: C

    Solution :

     Key Idea: \[{{W}_{0}}=h{{v}_{0}}\] where \[{{W}_{0}}=\]work function \[=3.13\text{ }eV\] \[{{W}_{0}}=h{{v}_{0}}\] or \[{{v}_{0}}=\frac{{{W}_{0}}}{h}=\frac{3.13\times 1.6\times {{10}^{-19}}}{6.6\times {{10}^{-34}}}\] \[=0.758\times {{10}^{14}}\,Hz\] \[\therefore \] Threshold frequency \[({{v}_{0}})\simeq 8\times {{10}^{15}}Hz\]


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