BCECE Medical BCECE Medical Solved Papers-2001

  • question_answer
    In the equation \[\left( p+\frac{a}{{{V}^{2}}} \right)\,(V-b)=RT\], where P = pressure, V = volume, a and b are constants, the dimensions of a are :

    A)  \[[M{{L}^{5}}{{T}^{-1}}]\]      

    B)  \[[M{{L}^{-5}}{{T}^{-1}}]\]

    C)  \[[M{{L}^{5}}{{T}^{-2}}]\]

    D)  \[[{{M}^{-1}}{{L}^{5}}{{T}^{2}}]\]

    Correct Answer: C

    Solution :

    Key Idea: According to principle of homogeneity of dimensions, the dimensions of all the terms in a physical expression should be same. We have given                 \[\left( p+\frac{a}{{{V}^{2}}} \right)\,(V-b)=RT\] According to principle of homogeneity,                 \[[p]=\left[ \frac{a}{{{V}^{2}}} \right]\] or            \[[a]=[p]\,[{{V}^{2}}]\] or            \[[a]=[M{{L}^{-1}}{{T}^{-2}}]\,[{{L}^{6}}]\] \[\therefore \] \[[a]=[M{{L}^{5}}{{T}^{-2}}]\] Note : The physical quantities separated by the symbols +, - , =, > , < etc., have the same dimensions.


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