JEE Main & Advanced Physics Atomic Physics Question Bank Self Evaluation Test - Atoms

  • question_answer
    The ionization energy of a hydrogen like Bohr atom is 4 Rydbergs. Find the wavelength of the radiation emitted when the electron jumps from the first excited state to the ground state

    A)  \[300A{}^\circ \]

    B)  \[2.5\times {{10}^{-11}}m\]

    C)  \[100A{}^\circ \]

    D)  \[1.5\times {{10}^{-11}}m\]

    Correct Answer: A

    Solution :

    [a] \[{{E}_{n}}=-\frac{I.E.}{{{n}^{2}}}\] for Bohr "s hydrogen atom. Here, \[I.E/=4R\text{     }\therefore {{E}_{n}}=\frac{-4R}{{{n}^{2}}}\] \[\therefore {{E}_{2}}-{{E}_{1}}=\frac{-4R}{{{2}^{2}}}-\left( -\frac{4R}{{{l}^{2}}} \right)=3R\]                     ?.(i) \[{{E}_{2}}-{{E}_{1}}=hv=\frac{hc}{\lambda }\]                                 ?(ii) From (i) and (ii) \[\therefore \lambda =\frac{hc}{3R}=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{2.2\times {{10}^{-18}}\times 3}=300\overset{\text{o}}{\mathop{\text{A}}}\,\]


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