VIT Engineering VIT Engineering Solved Paper-2008

  • question_answer
    An electron microscope is used to probe the atomic arrangements to a resolution of 5 A. What should be the electric potential to which the electrons need to be accelerated?

    A)  2.5V          

    B)  5V

    C)  2.5 kV         

    D)  5kV  

    Correct Answer: B

    Solution :

    \[\lambda =\frac{h}{\sqrt{2eVm}}\] \[5\overset{\text{o}}{\mathop{\text{A}}}\,=\frac{6.6\times {{10}^{-34}}}{\sqrt{2\times 1.6\times {{10}^{-19}}\times 9.1\times {{10}^{-31}}\times V}}\] \[5\overset{\text{o}}{\mathop{\text{A}}}\,=\frac{6.6\times {{10}^{-34}}}{5.4\times {{10}^{-25}}\sqrt{V}}\] \[V={{\left( \frac{6.6\times {{10}^{-34}}}{5.4\times {{10}^{-25}}\times 5\times {{10}^{-10}}} \right)}^{2}}\] \[V=5.76volt\]


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