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

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

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

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

    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\[R\] \[\text{=}\frac{\text{ }\!\![\!\!\text{ Dimensions}\,\,\text{of}\,\,\text{work }\!\!]\!\!\text{ }}{\text{ }\!\![\!\!\text{ Dimensions}\,\,\text{of}\,\,\text{charge }\!\!]\!\!\text{ }\,\,\text{ }\!\![\!\!\text{ Dimensions}\,\,\text{of}\,\,\text{current }\!\!]\!\!\text{ }}\] \[=\frac{[M{{L}^{2}}{{T}^{-2}}]}{[IT][I]}=[M{{L}^{2}}{{T}^{-3}}{{I}^{-2}}]\]


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