JEE Main & Advanced Physics Photo Electric Effect, X- Rays & Matter Waves Question Bank Topic Test - Photo Electric Effect, X-Rays & Matter Waves

  • question_answer
    The kinetic energy of an electron with de-Broglie wavelength of 0.3 nanometer is        

    A) 0.168 eV

    B) 16.8 eV

    C) 1.68 eV

    D) 2.5 eV

    Correct Answer: B

    Solution :

    [b] \[\lambda =\frac{h}{\sqrt{2mE}}\Rightarrow E=\frac{{{h}^{2}}}{2m{{\lambda }^{2}}}\] \[=\frac{{{(6.6\times {{10}^{-34}})}^{2}}}{2\times 9.1\times {{10}^{-31}}\times {{(0.3\times {{10}^{-9}})}^{2}}}=2.65\times {{10}^{-18}}J\] \[=16.8\,eV\]

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