BCECE Medical BCECE Medical Solved Papers-2004

  • question_answer
    Dimensions of Plancks constant is :

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

    B) \[[ML{{T}^{-2}}]\]

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

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

    Correct Answer: A

    Solution :

    Key Idea: Place the dimensions for quantities involved in the expression comprising Plancks constant. Energy of photon                 \[E=h\times v\] where h is Plancks constant and v the frequency. \[\Rightarrow \] \[h=\frac{E}{v}\] \[\therefore \] \[[h]=\frac{[E]}{[v]}=\frac{[M{{L}^{2}}{{T}^{-2}}]}{[{{T}^{-1}}]}=[M{{L}^{2}}{{T}^{-1}}]\] Alternative : Unit of Plancks constant = joule \[\times \] second So, dimensions of Plancks constant                  \[=[M{{L}^{2}}{{T}^{-2}}]\,[T]\] \[=[M{{L}^{2}}{{T}^{-1}}]\]


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