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JEE Main & Advanced JEE Main Paper (Held On 10 April 2016)

  • question_answer
    A photoelectric surface is illuminated successively by monochromatic light of wavelengths \[\]and\[\frac{}{3}\]. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 time that in the first case, the work function of the surface is :   JEE Main Online Paper (Held On 10 April 2016)

    A) \[\frac{3hc}{}\]                                    

    B) \[\frac{hc}{}\]

    C) \[\frac{hc}{3}\]                                    

    D) \[\frac{hc}{2}\]

    Correct Answer: D

    Solution :

                 \[K{{E}_{1}}=\frac{hc}{}-W\]                          ...????.. (i)              \[3K.{{E}_{1}}=\frac{2hc}{}-W\]                    \[\Rightarrow \,K.{{E}_{1}}=\frac{2hc}{3}-\frac{W}{3}\]     ???..(ii) \[\Rightarrow \,\frac{hc}{}-W=\frac{2hc}{3}-\frac{W}{3}\] (Equating (i) & (ii)) \[\Rightarrow \,\frac{hc}{}\left( \frac{1}{3} \right)=\frac{2W}{3}\] \[\Rightarrow \,W=\frac{hc}{2}\]


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