JEE Main & Advanced Physics Photo Electric Effect, X- Rays & Matter Waves Question Bank Topic Test - Photo Electric Effect, X-Rays & Matter Waves

  • question_answer
    Ultraviolet radiations of \[6.2\,eV\] falls on an aluminium surface (work function \[4.2\ eV\]). The kinetic energy in joules of the fastest electron emitted is approximately   

    A) \[3.2\times {{10}^{-21}}\]

    B) \[3.2\times {{10}^{-19}}\]

    C) \[3.2\times {{10}^{-17}}\]

    D) \[3.2\times {{10}^{-15}}\]

    Correct Answer: B

    Solution :

    [b] \[{{K}_{\max }}(eV)=E\,(eV)-{{W}_{0}}\,(eV)\]\[=6.2-4.2=2\ eV\] \[\therefore \,\,\,\,\,{{K}_{\max }}(Joules)=\]\[2\times 1.6\times {{10}^{-19}}J=3.2\times {{10}^{-19}}J\]

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