NEET Sample Paper NEET Sample Test Paper-16

  • question_answer Let\[{{K}_{1}}\]be the maximum kinetic energy of photo electrons emitted by light of wavelength\[{{\lambda }_{1}}\]and\[{{K}_{2}}\]corresponding to wavelength\[{{\lambda }_{2}}.\]If \[{{\lambda }_{1}}=2{{\lambda }_{2}},\] then

    A) \[2{{K}_{1}}={{K}_{2}}\]             

    B) \[{{K}_{1}}=2{{K}_{2}}\] 

    C)      \[{{K}_{1}}<{{K}_{2}}/2\]

    D)      \[{{K}_{1}}>2{{K}_{2}}\]  

    Correct Answer: C

    Solution :

    \[\frac{hc}{{{\lambda }_{1}}}-{{\phi }_{0}}={{K}_{1}}\]and \[\frac{hc}{{{\lambda }_{1}}/2}-{{\phi }_{0}}={{K}_{2}}\] \[\Rightarrow \]\[{{K}_{2}}+{{\phi }_{0}}=2({{K}_{1}}+{{\phi }_{0}})\] \[\Rightarrow \]\[{{K}_{2}}+2{{K}_{1}}+{{\phi }_{0}}\] \[\Rightarrow \]\[{{K}_{2}}>2{{K}_{1}}\]\[\therefore \]\[{{K}_{1}}<{{K}_{2}}/2\] Hence, the correction option is (c).

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