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 radiation emitted when the electron jumps from the first excited state to the ground state: [1 Rydberg \[=2.2\times {{10}^{-18}},h=6.6\times {{10}^{-34}}Js,\] \[c=3\times {{10}^{8}}m/s\]. Bohr radius of hydrogen atom \[=5\times {{10}^{-11}}m\]

    A)  \[400\overset{\text{o}}{\mathop{\text{A}}}\,\]

    B)  \[300\overset{\text{o}}{\mathop{\text{A}}}\,\]

    C)  \[500\overset{\text{o}}{\mathop{\text{A}}}\,\]

    D)  \[600\overset{\text{o}}{\mathop{\text{A}}}\,\]

    Correct Answer: B

    Solution :

    [b] The energy in the ground state \[{{E}_{1}}=-\,4Rydberg\text{     }{{E}_{1}}=-\,4\times 2.2\times {{10}^{-18}}J\] The energy of the first excited state (n=2) \[{{E}_{2}}=\frac{{{E}_{1}}}{4}=2.2\times {{10}^{-18}}J\] The energy difference \[\Delta E={{E}_{2}}-{{E}_{1}}=3\times 2.2\times {{10}^{-18}}J\] Now, the wavelength of radiation emitted is \[\lambda =\frac{hc}{\Delta E}\] \[\lambda =\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{3\times 2.2\times {{10}^{-18}}}=300\overset{\text{o}}{\mathop{\text{A}}}\,\]


You need to login to perform this action.
You will be redirected in 3 sec spinner