JEE Main & Advanced JEE Main Paper Phase-I (Held on 09-1-2020 Morning)

  • question_answer
    The de Broglie wavelength of an electron in the \[{{4}^{th}}\] Bohr orbit is [JEE MAIN Held on 09-01-2020 Morning]

    A) \[4\pi {{a}_{0}}\]         

    B) \[6\pi {{a}_{0}}\]

    C) \[8\pi {{a}_{0}}\]         

    D) \[2\pi {{a}_{0}}\]

    Correct Answer: C

    Solution :

    [c] According to Bohr's model \[{{r}_{n}}=\frac{{{n}^{2}}}{Z}\times {{a}_{0}}\] (\[{{a}_{0}}={{1}^{st}}\]Bohr radius) \[\because 2\pi r=n\lambda \]       (using de-Broglie relation) \[\Rightarrow 2\pi \times \frac{{{4}^{2}}}{1}\times {{a}_{0}}=4\lambda \] \[\Rightarrow \lambda =8\pi {{a}_{0}}\]


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