NEET Physics Atomic Physics NEET PYQ-Atomic Physics

  • question_answer
    Which of the following transitions gives photon of maximum energy?                        [AIPMT 2000]

    A)  \[n=1\] to \[n=2\]

    B)       \[n=2\] to \[n=1\]

    C)  \[n=2\] to \[n=6\]         

    D)  \[n=6\] to \[n=2\]

    Correct Answer: B

    Solution :

    Energy level of H-atom are given by
    \[{{E}_{n}}=-\frac{13.6}{{{n}^{2}}}eV\]
                Photons are emitted only when electron jump from higher energy level (higher n-value) to lower energy level (lower n-value). So alternative  and  are wrong. Energy difference from \[n=2\]to \[n-1\] level is
    \[\Delta {{E}_{2\to 1}}=13.6\,\left( \frac{1}{{{1}^{2}}}-\frac{1}{{{2}^{2}}} \right)eV\]
    \[=13.6\times \frac{3}{4}=10.2\,eV\]
                Energy difference from \[n=6\]to \[n=2\] level is
                \[\Delta {{E}_{6\to 2}}=13.6\,\left( \frac{1}{{{2}^{2}}}-\frac{1}{{{6}^{2}}} \right)eV\]           
                \[=13.6\times \left( \frac{1}{4}-\frac{1}{36} \right)eV\]
                \[=13.6\times \frac{2}{9}eV\]
                \[=3.02\text{ }eV\]
    Thus, it is evident that difference is larger for \[n=2\] to \[n=1\] transition. Hence, maximum energy   photon   will   be emitted during transition from \[n=2\] to \[n=1\].


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