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KVPY Sample Paper KVPY Stream-SX Model Paper-3

  • question_answer
    A parallel beam of monochromatic radiation of cross-section area \[A\,(<\pi {{a}^{2}}),\] intensity I and frequency \[\nu \] is incident on a solid conducting sphere of work function \[{{\phi }_{0}}\,[h\nu >{{\phi }_{0}}]\] and radius 'a'. The sphere is grounded by a conducting wire Assume that for each incident photon one photoelectron is ejected. Just after this radiation is incident on initially uncharged sphere, the current through the conducting wire is:

    A) \[\frac{IAe}{h\nu }\]                              

    B) \[\frac{IAe}{2h\nu }\]

    C) \[\frac{2IAe}{h\nu }\]                

    D) none of these

    Correct Answer: A

    Solution :

    Number of photons incident on sphere per second\[=\frac{I\,A}{h\,\nu }\] \[\therefore \]photo electrons ejected per second\[=\frac{I\,A}{h\,\nu }\] \[\therefore \]current through conducting wire = photo current ejected from surface of sphere \[=\frac{I\,Ae}{h\,\nu }\]


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