AMU Medical AMU Solved Paper-2010

  • question_answer
    According to the Bohr theory of hydrogen atom, the speed of the electron, its energy and the radius of its orbit varies with the principal quantum number n, respectively, as

    A)  \[\frac{1}{n},\frac{1}{{{n}^{2}}},{{n}^{2}}\]                         

    B)  \[\frac{1}{n},{{n}^{2}},\frac{1}{{{n}^{2}}}\]

    C)  \[{{n}^{2}},\frac{1}{{{n}^{2}}},{{n}^{2}}\]                            

    D)  \[n,\frac{1}{{{n}^{2}}},\frac{1}{{{n}^{2}}}\]

    Correct Answer: A

    Solution :

                     According to Booths theory of hydrogen atom (i) The speed of electron in nth orbit                 \[{{v}_{n}}=\frac{Z{{e}^{2}}}{2{{\varepsilon }_{0}}nh}\] or \[{{v}_{n}}\propto \frac{1}{n}\] (ii) The energy of electron in the nth orbit                 \[{{E}_{n}}-\left( \frac{m{{e}^{4}}}{8\varepsilon _{0}^{2}{{h}^{2}}} \right).\,\frac{{{Z}^{2}}}{{{n}^{2}}}=-13.6\frac{{{Z}^{2}}}{{{n}^{2}}}eV\] or            \[{{E}_{n}}\propto \frac{1}{{{n}^{2}}}\]  (iii) The radius of the electron in the nth orbit                 \[{{r}_{n}}=\frac{{{n}^{2}}{{h}^{2}}{{\varepsilon }_{0}}}{\pi mZ{{e}^{2}}}=0.53\frac{{{n}^{2}}}{2}\overset{o}{\mathop{A}}\,\] So, option  is correct.


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