J & K CET Engineering J and K - CET Engineering Solved Paper-2003

  • question_answer
    If the electron in hydrogen atom jumps from the third to second orbit, the wavelength of the emitted radiation in terms of Rydberg constant R is given by

    A)  \[\lambda =\frac{36}{5R}\]

    B)  \[\lambda =\frac{5R}{36}\]

    C)  \[\lambda =\frac{5}{R}\]

    D)  \[\lambda =\frac{R}{6}\]

    Correct Answer: A

    Solution :

    From Bohr's model of atom, the wave number is given by \[\frac{1}{\lambda }=R\left( \frac{1}{{{n}_{1}}^{2}}-\frac{1}{{{n}_{2}}^{2}} \right)\] where R is Rydberg's constant and \[{{n}_{1}}\] and \[{{n}_{2}}\] the energy levels. Given,     \[{{n}_{1}}=2,\,\,\,\,{{n}_{2}}=3\] \[\therefore \] \[\frac{1}{\lambda }=R\left( \frac{1}{{{2}^{2}}}-\frac{1}{{{3}^{2}}} \right)\] \[\frac{1}{\lambda }=R\left[ \frac{5}{36} \right]\] \[\Rightarrow \] \[\lambda =\frac{36}{5R}\] This gives the corresponding wavelength of Balmer series.


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