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 de-Broglie wavelength of an electron having \[80eV\] of energy is nearly             (\[1\,eV=\text{ }1.6\times {{10}^{19}}J,\]  Mass of electron \[=9\times {{10}^{-31}}kg\] Plank’s constant \[=6.6\times {{10}^{-34}}J\text{-}\,\sec \])

    A) 140 \[\overset{\text{o}}{\mathop{\text{A}}}\,\]

    B) 0.14 \[\overset{\text{o}}{\mathop{\text{A}}}\,\]

    C) 14 \[\overset{\text{o}}{\mathop{\text{A}}}\,\]

    D) 1.4 \[\overset{\text{o}}{\mathop{\text{A}}}\,\]

    Correct Answer: B

    Solution :

    [b] If an electron and a photon propagates in the from of waves having the same wavelength, it implies that they have same momentum. This is according to de-Broglie equation, \[p\propto \frac{1}{\lambda }\]

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