JEE Main & Advanced Physics Nuclear Physics And Radioactivity Question Bank Critical Thinking

  • question_answer
    The ionisation potential of H-atom is \[13.6\,V\]. When it is excited from ground state by monochromatic radiations of \[970.6\,{AA}\], the number of emission lines will be (according to Bohr?s theory)                                          [RPET 1999]

    A) 10  

    B) 8

    C) 6    

    D) 4

    Correct Answer: C

    Solution :

    \[\frac{1}{\lambda }=R\left[ \frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}} \right]\]                    \[\Rightarrow \frac{1}{970.6\times {{10}^{-10}}}=1.097\times {{10}^{7}}\left[ \frac{1}{{{1}^{2}}}-\frac{1}{n_{2}^{2}} \right]\]\[\Rightarrow {{n}_{2}}=4\]                    \[\therefore \]Number of emission lines \[N=\frac{n(n-1)}{2}=\frac{4\times 3}{2}=6\]                               


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