BCECE Engineering BCECE Engineering Solved Paper-2006

  • question_answer
    A certain electrical conductor has a square cross-section, 2.0 mm on side, and is 12 m long. The resistance between its ends is 0.072\[\Omega .\] The resistivity of its material is equal to :

    A) \[2.4\times {{10}^{-6}}\Omega m\]                        

    B)         \[1.2\times {{10}^{-6}}\Omega m\]

    C)        \[1.2\times {{10}^{-8}}\Omega m\]                        

    D)         \[2.4\times {{10}^{-8}}\Omega m\]

    Correct Answer: D

    Solution :

    The resistance R of a particular conductor is related to the resistivity \[\rho \]of its material by \[R=\frac{\rho l}{A}\]                 or            \[\rho =\text{resistivity}=\frac{RA}{l}\]                 Given, \[R=0.072\,\Omega ,\] \[A=2\,mm\times 2\,mm=4\times {{10}^{-6}}{{m}^{2}},l=12\,mm\] \[\therefore \]  \[\rho =\frac{0.072\times 4\times {{10}^{-6}}}{12}\] \[=0.024\times {{10}^{-6}}\Omega \,m\]             \[=2.4\times {{10}^{-8}}\Omega \,m\]


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