JEE Main & Advanced AIEEE Solved Paper-2006

  • question_answer
    The threshold frequency for a metallic surface corresponds to an energy of 6.2 eV and the stopping potential for a radiation incident on this surface is 5V. The incident radiation lies in     AIEEE  Solved  Paper-2006

    A) ultraviolet region

    B) infrared region

    C) visible region

    D) X-ray region

    Correct Answer: A

    Solution :

    The threshold energy,\[h{{v}_{0}}=6.2\text{ }eV\]and the stopping potential\[e{{V}_{0}}=5\text{ }eV\] From Einstein's photoelectric equation, \[hv=h{{v}_{0}}+e{{V}_{0}}=6.2+5=11.2\,eV\]                                                 \[(\because hv={{\phi }_{0}}+KE)\] \[\Rightarrow \] \[\frac{hc}{\lambda }=11.2\,eV;\]where,\[\lambda \]is the wavelength. \[\therefore \]\[\lambda =\frac{hc}{112(eV)}=1108.9{\AA}\] Which belongs to ultraviolet region.


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