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NEET Sample Paper NEET Sample Test Paper-79

  • question_answer
    In a photoelectric effect measurement, the stopping potential for a given metal is found to be \[{{V}_{0}}\] volt when radiation of wavelength \[{{\lambda }_{0}}\] is used. If radiation of wavelength \[2\,{{\lambda }_{0}}\] is used with the same metal then the stopping potential (in volt) will be

    A)  \[\frac{{{V}_{0}}}{2}\]                                   

    B)  \[\,2\,{{V}_{0}}\]

    C)  \[{{V}_{0}}+\frac{hc}{2e{{\lambda }_{0}}}\]             

    D)  \[{{V}_{0}}-\frac{hc}{2e{{\lambda }_{0}}}\]

    Correct Answer: D

    Solution :

    As \[e{{V}_{0}}=\frac{hc}{{{\lambda }_{0}}}={{W}_{0}}\]                            ? (i) and \[eV'=\frac{hc}{2{{\lambda }_{0}}}-{{W}_{0}}\]                            ... (ii) Subtracting Eq. (i) from Eq. (ii) \[e({{V}_{0}}-V')\,\,=\,\,\frac{hc}{{{\lambda }_{0}}}\,\left( 1-\frac{1}{2} \right)\] \[=\,\,\,\frac{hc}{2{{\lambda }_{0}}}\] \[V'={{V}_{0}}-\frac{hc}{2e{{\lambda }_{0}}}\]


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