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BHU PMT BHU PMT (Screening) Solved Paper-2008

  • question_answer
    There is a current of 40 A in a wire of\[{{10}^{-6}}{{m}^{2}}\]area of cross-section. If the number of free electrons per cubic metre is\[{{10}^{29}},\]then the drift velocity is

    A)  \[250\times {{10}^{-3}}m/s\]    

    B)  \[25.0\times {{10}^{-3}}m/s\]

    C)  \[2.50\times {{10}^{-3}}m/s\]   

    D)  \[1.25\times {{10}^{3}}m/s\]

    Correct Answer: C

    Solution :

                     Drift velocity \[{{v}_{d}}=\frac{i}{neA}\]                 \[=\frac{40}{{{10}^{29}}\times 1.6\times {{10}^{-19}}\times {{10}^{-6}}}\] \[=2.5\times {{10}^{-3}}m/s\]


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