BCECE Engineering BCECE Engineering Solved Paper-2011

  • question_answer
    A current of 0.01 mA passes through the potentiometer wire of a resistivity of \[{{10}^{9}}\Omega \] and area of cross-section \[{{10}^{-2}}c{{m}^{2}}\]. The potential gradient is

    A)  \[\text{1}{{\text{0}}^{\text{9}}}\text{V/m}\]                                   

    B)  \[\text{1}{{\text{0}}^{11}}\text{V/m}\]

    C) \[\text{1}{{\text{0}}^{10}}\text{V/m}\]                

    D)         \[\text{1}{{\text{0}}^{8}}\text{V/m}\]

    Correct Answer: D

    Solution :

    Potential gradient is \[k=\frac{V}{l}=\frac{iR}{l}\]                        \[(\therefore \,V=iR)\] \[=\frac{i\times \rho \frac{l}{A}}{l}\]                       \[\left( \because \,R=\rho \frac{l}{A} \right)\] \[=\frac{i\rho }{A}\]                 \[\therefore \]    \[k=\frac{0.01\times {{10}^{-3}}\times {{10}^{9}}\times {{10}^{-2}}}{{{10}^{-2}}\times {{10}^{-4}}}={{10}^{8}}V/m\]


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