BCECE Engineering BCECE Engineering Solved Paper-2012

  • question_answer
    In hydrogen atom, energy of first excited state is \[-3.4\text{ }eV.\] Then KE of same orbit of hydrogen atom

    A) \[+\text{ }3.4eV\]       

    B)         \[+\text{ }6.8\text{ }eV\]           

    C)        \[~-\text{ }13.6\text{ }eV\]      

    D)         \[+\text{ }13.6\text{ }eV\]

    Correct Answer: A

    Solution :

    \[\because \]Total energy \[({{E}_{n}})=KE\,+PE\] In first excited state \[=\frac{1}{2}m{{v}^{2}}+\left[ -\frac{Z{{e}^{2}}}{r} \right]\]                                 \[=+\frac{1}{2}{{\frac{Ze}{r}}^{2}}-\frac{Z{{e}^{2}}}{r}-3.4\,eV\]                                 \[=-\frac{1}{2}\frac{Z{{e}^{2}}}{r}\]                 \[\therefore \]  \[KE=\frac{1}{2}\frac{Z{{e}^{2}}}{r}=+3.4\,eV\]


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