NEET Sample Paper NEET Sample Test Paper-44

  • question_answer
    Light of two different frequencies whose photons have energy leV and 2eV respectively, illuminate a metallic surface whose work function is 0.5eV successfully. Ratio of maximum speeds of emitted electrons will be:

    A) 1:2                   

    B) 1:1   

    C) 1: 5                  

    D) 1:4

    Correct Answer: A

    Solution :

    \[{{\operatorname{E}}_{1}}=leV~~~~~{{\phi }_{1}}={{\phi }_{2}} = 0.5eV\] \[{{\operatorname{E}}_{2}}=2.5eV\] Equation of photoelectric effect \[{{\operatorname{E}}_{1}}={{\phi }_{1}}+ K{{E}_{1}}~~, {{E}_{2}}=~\phi + KE2\] \[1=0.5+\frac{1}{2}m{{v}^{2}}_{1},2.5=0.5+\frac{1}{2}m{{v}^{2}}_{2}\] \[\frac{0.5\times 2}{\operatorname{m}}={{\operatorname{v}}^{2}}_{1},\frac{2\times 2}{\operatorname{m}}={{\operatorname{v}}^{2}}_{2}\] \[{{\left[ \frac{{{v}_{1}}}{{{v}_{2}}} \right]}^{2}}=\frac{1}{4}\] \[\frac{{{v}_{1}}}{{{v}_{2}}}=\frac{1}{2}\]1`


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