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WB JEE Medical WB JEE Medical Solved Paper-2006

  • question_answer
    At room temperature, copper has free electron density of \[8.4\times {{10}^{28}}{{m}^{-3}}.\] The electron drift velocity   in   a   copper   conductor   of cross-sectional area of \[{{10}^{-6}}{{m}^{2}}\]and carrying a current of 5.4 A, will be :

    A)  \[4\,m{{s}^{-1}}\]                          

    B)  \[0.4\,m{{s}^{-1}}\]

    C)  \[4\,cm\,{{s}^{-1}}\]                     

    D)  \[0.4\,mm\,{{s}^{-1}}\]

    Correct Answer: D

    Solution :

                     Drift velocity, \[{{v}_{d}}=\frac{I}{neA}\] \[=\frac{5.4}{8.4\times {{10}^{28}}\times 1.6\times {{10}^{-19}}\times {{10}^{-6}}}\] \[=0.4\times {{10}^{-3}}\,m{{s}^{-1}}\] \[=0.4\,mm{{s}^{-1}}\]


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