VMMC VMMC Medical Solved Paper-2003

  • question_answer
    The light of wavelength 4000 \[\overset{0}{\mathop{A}}\,\] falls on a photosensitive substance whose work function is 2 eV. Its stopping potential is:

    A)  1.1 V                                    

    B)  1.8 V                    

    C)  1.26 V                  

    D)         0.8 V

    Correct Answer: A

    Solution :

    Using the relation, \[e{{V}_{s}}=\frac{hc}{\lambda }-\text{o }\!\!|\!\!\text{ }\] \[{{V}_{s}}=\]stopping potential \[\text{o }\!\!|\!\!\text{ =}\]work function of the substance \[{{V}_{s}}=\frac{hc}{e\lambda }-\frac{\text{o }\!\!|\!\!\text{ }}{e}\] \[=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{1.6\times {{10}^{-19}}\times 4000\times {{10}^{-10}}}-\frac{2\times 1.6\times {{10}^{-19}}}{1.6\times {{10}^{-19}}}\] \[=3.1-2\] \[=1.1\,V\]


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