JEE Main & Advanced Physics Atomic Physics Question Bank Self Evaluation Test - Atoms

  • question_answer
    The wavelength of \[{{K}_{a}}\] X-rays produced by an X-ray tube is 0.76 A. Find the atomic number of the anode material of the tube?

    A)  40

    B)  30   

    C)  20

    D)  10

    Correct Answer: A

    Solution :

    [a] \[\frac{1}{\lambda }=R{{Z}^{2}}\left( \frac{1}{{{1}^{2}}}-\frac{1}{{{2}^{2}}} \right)=\frac{3}{4}R{{Z}^{2}}\] \[or\text{    }{{Z}^{2}}=\frac{4}{3R\lambda }\] \[=\frac{4}{3\times \left( 1.097\times {{10}^{7}} \right)\times \left( 0.76\times {{10}^{-10}} \right)}=1599.25\] \[or\text{     }{{Z}^{2}}=1600\text{       }\therefore Z=40.\]


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