JEE Main & Advanced Physics Photo Electric Effect, X- Rays & Matter Waves Question Bank Self Evaluation Test - Dual Nature of Radiation and Matter

  • question_answer
    The threshold wavelength of the tungsten is 2300 If ultraviolet light of wavelength \[1800\text{ }\overset{\text{o}}{\mathop{\text{A}}}\,\] is incident on it, then the maximum kinetic energy of photoelectrons would be about

    A) 1.49eV

    B) 2.2eV

    C) 3.0eV

    D) 5.0eV

    Correct Answer: A

    Solution :

    [a] \[{{K}_{\max }}=hv-h{{v}_{0}}=hc\left( \frac{1}{\lambda }-\frac{1}{{{\lambda }_{0}}} \right)\] Use \[hc=1.24\times {{10}^{-6}}\left( eV \right)m\] \[hc=1.24\times {{10}^{-6}}\left( \frac{{{10}^{8}}}{18}-\frac{{{10}^{8}}}{23} \right)\] \[=\frac{1.24\times 100\times \left( 23-18 \right)}{18\times 23}=1.49eV\]


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