BHU PMT BHU PMT (Screening) Solved Paper-2009

  • question_answer
    The energy of an electron in the 3rd orbit of an atom is\[-E\]. The energy of an electron in the first orbit will be

    A)  \[-3E\]                

    B)  \[-\frac{E}{3}\]

    C)  \[-\frac{E}{9}\]                

    D) \[-9E\]

    Correct Answer: D

    Solution :

                     \[{{E}_{n}}=-\frac{13.6{{Z}^{2}}}{{{n}^{2}}}\] \[{{E}_{n}}\propto \frac{1}{{{n}^{2}}}\] \[\therefore \]  \[\frac{{{E}_{3}}}{{{E}_{1}}}={{\left( \frac{{{n}_{1}}}{{{n}_{3}}} \right)}^{2}}\]                 \[\frac{-E}{{{E}_{1}}}={{\left( \frac{1}{3} \right)}^{2}}=\frac{1}{9}\] \[\therefore \]  \[{{E}_{1}}=-9E\]


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