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JEE Main & Advanced Physics Photo Electric Effect, X- Rays & Matter Waves Question Bank Self Evaluation Test - Dual Nature of Radiation and Matter

  • question_answer
    An X-ray tube with Cu target is operated at 25 kV. The glancing angle for a \[NaCl.\] Crystal for the \[Cu\]\[{{K}_{\alpha }}\]  line is \[15.8{}^\circ \]. Find the wavelength of this line. (\[NaCl=2.82\overset{\text{o}}{\mathop{\text{A}}}\,\] for, \[\text{h=6}\text{.62 }\!\!\times\!\!\text{ 1}{{\text{0}}^{-\,27}}\text{erg-sec}\])

    A) 3.06 A

    B) 1.53 A

    C) 0.75 A

    D) None of these

    Correct Answer: B

    Solution :

    [b] According to Bragg's law, \[2d\sin \theta =n\lambda \], n = 1 for first order \[\Rightarrow 2\times 2.82\sin 15.8=\lambda \] \[\Rightarrow \lambda =5.64\times 0.2723=1.53\overset{\text{o}}{\mathop{\text{A}}}\,\]


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