JCECE Engineering JCECE Engineering Solved Paper-2008

  • question_answer
    Dimensions of resistance in an electrical circuit, in terms of dimension of mass\[M\], of length\[L\], of time \[T\] and of current\[I\], would be

    A) \[[M{{L}^{2}}{{T}^{-3}}{{I}^{-1}}]\]                          

    B) \[[M{{L}^{2}}{{T}^{-2}}]\]

    C)  \[[M{{L}^{2}}{{T}^{-1}}{{I}^{-1}}]\]                         

    D)  \[[M{{L}^{2}}{{T}^{-3}}{{I}^{-2}}]\]

    Correct Answer: D

    Solution :

    Resistance                 \[R=\frac{potential\,\,difference}{current}=\frac{V}{i}=\frac{W}{qi}\] \[(\because \]Potential difference is equal to work done per unit charge) So, Dimensions of\[R\] \[=\frac{\text{ }\!\![\!\!\text{ Dimensions}\,\,\text{of}\,\,\text{work }\!\!]\!\!\text{ }}{\text{ }\!\![\!\!\text{ Dimensions}\,\,\text{of}\,\,\text{charge }\!\!]\!\!\text{  }\!\![\!\!\text{ Dimensions}\,\,\text{of}\,\,\text{current }\!\!]\!\!\text{ }}\]\[=\frac{[M{{L}^{2}}{{T}^{-2}}]}{[IT][I]}=[M{{L}^{2}}{{T}^{-3}}{{I}^{-2}}]\]


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