NEET NEET SOLVED PAPER 2016 Phase-II

  • question_answer
    Electrons of mass m with de-Broglie wavelength λ fall on the target in an X-ray tube. The cutoff wavelength \[{{\lambda }_{0}}\] of the emitted X-ray is

    A)  \[{{\lambda }_{0}}=\frac{2mc{{\lambda }^{2}}}{h}\]

    B)  \[{{\lambda }_{0}}=\frac{2h}{mc}\]

    C)  \[{{\lambda }_{0}}=\frac{2{{m}^{2}}{{c}^{2}}{{\lambda }^{2}}}{{{h}^{2}}}\] 

    D)  \[{{\lambda }_{0}}=\lambda \]

    Correct Answer: A

    Solution :

    Momentum \[P=\frac{h}{\lambda }\Rightarrow E=\frac{{{P}^{2}}}{2m}\Rightarrow \frac{{{h}^{2}}}{2m{{\lambda }^{2}}}=\frac{hc}{{{\lambda }_{0}}}\] \[P=\frac{h}{\lambda }\Rightarrow {{\lambda }_{0}}=\frac{hc}{{{h}^{2}}}2m{{\lambda }^{2}}\] \[=\frac{2mc{{\lambda }^{2}}}{h}\]


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