Punjab Medical Punjab - MET Solved Paper-2007

  • question_answer
    The dimensions of\[\frac{{{e}^{2}}}{4\pi {{\varepsilon }_{0}}hc}\], where\[e,\,{{\varepsilon }_{0}},\,h\]and\[c\] are electronic charge, electric permittivity Plancks constant and velocity of light in vacuum respectively

    A) \[[{{M}^{0}}{{L}^{0}}{{T}^{0}}]\]                               

    B) \[[M{{L}^{0}}{{T}^{0}}]\]

    C) \[[{{M}^{0}}L{{T}^{0}}]\]                              

    D) \[[{{M}^{0}}{{L}^{0}}T]\]

    Correct Answer: A

    Solution :

    \[[e]=AT,\,\,{{\varepsilon }_{0}}=[{{M}^{-1}}{{L}^{-3}}{{T}^{4}}{{A}^{2}}]\] \[[h]=[M{{L}^{2}}{{T}^{-1}}]\]and\[[c]=[L{{T}^{-1}}]\] \[\therefore \]\[\left[ \frac{{{e}^{2}}}{4\pi {{\varepsilon }_{0}}hc} \right]=\left[ \frac{{{A}^{2}}{{T}^{2}}}{{{M}^{-1}}{{L}^{-3}}{{T}^{4}}{{A}^{2}}\times M{{L}^{2}}{{T}^{-1}}\times L{{T}^{-1}}} \right]\]                 \[=[{{M}^{0}}{{L}^{0}}{{T}^{0}}]\]


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