Chhattisgarh PMT Chhattisgarh PMT 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) \[\text{ }\!\![\!\!\text{ M}{{\text{L}}^{\text{2}}}{{\text{T}}^{-3}}{{\text{I}}^{\text{-1}}}\text{ }\!\!]\!\!\text{ }\]                               

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

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

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

    Correct Answer: D

    Solution :

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


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