JEE Main & Advanced Sample Paper JEE Main - Mock Test - 42

  • question_answer
    Find the ratio of longest wavelength and the shortest wavelength observed in the five spectral series of emission spectrum of hydrogen.

    A) \[\frac{4}{3}\]              

    B)        \[\frac{525}{376}\]

    C) \[25\]                

    D)        \[\frac{900}{11}\]

    Correct Answer: D

    Solution :

    Shortest wavelength comes from \[{{n}_{1}}=\infty \] to \[{{n}_{2}}=1\]and longest wavelength comes from \[{{n}_{1}}=6\] to \[{{n}_{2}}=5\] in the given case. Hence \[\frac{1}{{{\lambda }_{\min }}}=R\left( \frac{1}{{{1}^{2}}}-\frac{1}{{{\infty }^{2}}} \right)=R\] \[\frac{1}{{{\lambda }_{\max }}}=R\left( \frac{1}{{{5}^{2}}}-\frac{1}{{{6}^{2}}} \right)=R\left( \frac{36-25}{25\times 36} \right)=\frac{11}{900}R\] \[\therefore \,\,\frac{{{\lambda }_{\max }}}{{{\lambda }_{\min }}}=\frac{900}{11}\]


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