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NEET Sample Paper NEET Sample Test Paper-79

  • question_answer
    A copper wire of length 0.5 m and area of cross-section \[{{10}^{-\,3}}\,{{m}^{2}}\] carries a current of 0.1 A. If the resistivity of copper is \[1.8\,\,\times \,\,1{{0}^{-\,8}}\pi  m\], the electric field across the wire is

    A)  \[1.8\,\,\times 1{{0}^{-\,3}}\]              

    B)  \[1.8\,\,\times 1{{0}^{-\,6}}\]

    C)  \[1.8\,\,\times 1{{0}^{-\,9}}\]              

    D)  \[1.8\,\,\times 1{{0}^{-\,12}}\]

    Correct Answer: B

    Solution :

    As, \[R=\rho \frac{I}{A}\] and \[V=IR=I\,\left( \frac{\rho l}{A} \right)\] Now, electric field \[E=\frac{V}{I}=\frac{\rho l}{A}=\frac{0.1\times (1.8\,\,\times \,\,{{10}^{-\,8}})}{{{10}^{-\,3}}}\] \[=\,\,\,1.8 \times \,\,{{10}^{-\,}}^{6}\]


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