JEE Main & Advanced Physics Photo Electric Effect, X- Rays & Matter Waves Question Bank Self Evaluation Test - Dual Nature of Radiation and Matter

  • question_answer
    The threshold frequency for a metallic surfaces corresponds on an energy of 6.2 eV and the stopping potential for a radiation incident on this surface is 5V. The incident radiation lies in

    A) ultra-violet region

    B) infra-red region

    C) visible region  

    D) X-ray region

    Correct Answer: A

    Solution :

    [a] \[\phi =6.2eV=6.2\times 1.6\times {{10}^{-19}}J\] \[V=5volt\] \[\frac{hc}{\lambda }-\phi =e{{V}_{0}}\Rightarrow \lambda =\frac{hc}{\phi +e{{V}_{0}}}\] \[=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{1.6\times {{10}^{-19}}\left( 6.2+5 \right)}\] This range lies in ultra violet range.


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