JEE Main & Advanced Sample Paper JEE Main - Mock Test - 14

  • question_answer
    Given that a photon of light of wavelength 10,000 A has an energy equal to 1.23 eV. When light of wavelength \[5000\overset{\text{o}}{\mathop{\text{A}}}\,\] and intensity \[{{I}_{0}}\] falls on a photoelectric cell, the surface current is \[0.40\times {{10}^{-6}}A\]and the stopping potential is 1.36 V, then the work function is

    A) 0.43 eV         

    B) 0.55 eV

    C) 1.10 eV        

    D) 1.53 eV

    Correct Answer: C

    Solution :

    [c]: Energy of a photon\[E=\frac{hc}{\lambda }\]or\[E\propto \frac{1}{\lambda }\] \[\therefore \]\[\frac{{{E}_{2}}}{{{E}_{1}}}=\frac{{{\lambda }_{1}}}{{{\lambda }_{2}}}\] or\[{{E}_{2}}={{E}_{1}}\times \frac{{{\lambda }_{1}}}{{{\lambda }_{2}}}=1.23\times \frac{10000}{5000}=2.46eV\] According to Einstein?s photoelectric equation \[h\upsilon -{{\phi }_{0}}=\frac{1}{2}m{{v}^{2}}_{\max }=e{{V}_{s}}\] or\[{{\phi }_{0}}=h{{v}_{2}}-e{{V}_{s}}={{E}_{2}}-e{{V}_{s}}\]


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