NEET Physics Atomic Physics NEET PYQ-Atomic Physics

  • question_answer
    An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be                                                                    [AIPMT (S) 2012]

    A)  \[\frac{24\,hR}{25\,m}\]

    B)       \[\frac{25\,hR}{24\,m}\]

    C)  \[\frac{25\,m}{24\,h\,R}\]         

    D)       \[\frac{24\,m}{25\,h\,R}\]

    Correct Answer: A

    Solution :

    Here, \[{{E}_{5}}-{{E}_{1}}=\frac{hc}{\lambda }\]
    and       \[\frac{R\,hc}{25}-R\,hc=\frac{hc}{\lambda }\]
    \[\frac{24}{25}R\,=\frac{1}{\lambda }\]
    but        \[p=\frac{h}{\lambda }\]
    and       \[v=\frac{h}{m\lambda }\]
                \[=\frac{24}{25}\frac{Rh}{m}\]
    (m is the mass of the electron, R Rydberg constant and h Planck's constant)


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