NEET Physics Photo Electric Effect, X- Rays & Matter Waves NEET PYQ-Photo Electric Effect,X-Rays

  • question_answer
    The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work function \[5.01\text{ }eV,\] when ultraviolet light of 200nm falls on it, must be                       [AIPMT (S) 2010]

    A)  2.4 V   

    B)  \[-1.2\text{ }V\]

    C)  2.4 V   

    D)  1.2 V

    Correct Answer: D

    Solution :

    Energy of incident light
    \[E(eV)=\frac{12375}{2000}=6.2\,eV\,(200\,nm=2000{\AA})\]
    According to the relation \[E={{W}_{0}}+e{{V}_{0}}\]
    \[\Rightarrow \]   \[{{V}_{0}}=\frac{E-{{W}_{0}}}{e}\]
    \[=\frac{(6.2-5.01)e}{e}\]
                            \[=1.2\,V\]


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