J & K CET Engineering J and K - CET Engineering Solved Paper-2005

  • question_answer
    If the frequency of light incident on metal surface is doubled, then kinetic energy of emitted electron will become

    A)  doubled

    B)  less than double

    C)  more than double

    D)  nothing can be said

    Correct Answer: C

    Solution :

    From Einstein's photoelectric equation, we have \[{{E}_{k}}=hv-W\] where \[{{E}_{k}}\] is maximum kinetic energy of photoelectrons and W the work function \[(=h{{v}_{0}})\]. \[\therefore \] \[{{E}_{k}}=h(v-{{v}_{0}})\] ?.(i) where \[{{v}_{0}}\] is threshold frequency. For        \[hv'=2hv\] \[\therefore \] \[2{{E}_{k}}=2h(v-{{v}_{0}})\] ?..(ii) From Eqs. (i) and (ii), we observe that kinetic energy of emitted electron will become more than doubled.


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