JEE Main & Advanced Physics Photo Electric Effect, X- Rays & Matter Waves JEE PYQ-Photo Electric Effect X-rays

  • question_answer
    The de-Broglie wavelength\[({{\lambda }_{B}})\]associated with the electron orbiting in the second excited state of hydrogen atom is related to that in the ground state\[({{\lambda }_{G}})\]by [JEE Main Online 16-4-2018]

    A) \[{{\lambda }_{B}}={{\lambda }_{G/3}}\]

    B) \[{{\lambda }_{B}}={{\lambda }_{G/2}}\]

    C) \[{{\lambda }_{B}}=2{{\lambda }_{G}}\]

    D) \[{{\lambda }_{B}}=3{{\lambda }_{G}}\]

    Correct Answer: D

    Solution :

    [d] de-Broglie wavelength
    \[\lambda =\frac{h}{mv}\]
    \[mvr=\frac{nh}{2\pi }\]
    \[\frac{h}{mv}=\frac{2\pi r}{n}\]
    \[\lambda =\frac{2\pi r}{n}\]
    \[r={{a}_{0}}\frac{{{n}^{2}}}{Z}\]
    \[\lambda =\frac{2\pi {{a}_{0}}n}{Z}\]
    As the atom is hydrogen Z = 1
    \[{{\lambda }_{B}}=\frac{2\pi {{a}_{0}}3}{Z}\]
    \[{{\lambda }_{G}}=\frac{2\pi a0}{Z}\]
    \[{{\lambda }_{B}}=3{{\lambda }_{G}}\]


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