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CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2003

  • question_answer
    A potentiometer has uniform potential gradient. The specific resistance of the material of the potentiometer wire is \[{{10}^{-7}}\] ohm-metre and the current passing through it is 0.1 ampere, cross-section of the wire is 10 m. The potential gradient along the potentiometer wire is:

    A)  \[{{10}^{-6}}V/m\]        

    B)  \[{{10}^{-4}}V/m\]

    C)  \[{{10}^{-8}}V/m\]                        

    D)  \[{{10}^{-2}}V/m\]

    Correct Answer: D

    Solution :

    Given: Specific resistance \[\rho ={{10}^{-7}}\Omega -m\],\[A={{10}^{-6}}{{m}^{2}},\,i=0.1\,A\] Resistance of 1 metre length of wire                 \[R=\frac{\rho l}{A}=\frac{\rho \times 1}{A}={{10}^{-7}}/{{10}^{-1}}\Omega \] \[\therefore \] potential gradient = potential drop                                                 per unit length \[K=Ri={{10}^{-1}}\times 0.1={{10}^{-2}}\] volt/metre


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