NEET Physics Mathematical Tools, Units & Dimensions NEET PYQ-Mathematical Tools, Units and Dimensions

  • question_answer
    Which two of the following five physical parameters have the same dimensions?          [AIPMT (S) 2008]
    (1) energy density
    (2) refractive index                               
    (3) dielectric constant
    (4) Young's modulus                              
    (5) magnetic field

    A)                                 2 and 4

    B) 3 and 5

    C) 1 and 4

    D) 1 and 5                   

    Correct Answer: C

    Solution :

    (1) Energy density\[\text{=}\frac{\text{Energy}}{\text{Volume}}\]
    \[\text{=}\frac{[M{{L}^{2}}{{T}^{-2}}]}{[{{L}^{3}}]}=[M{{L}^{-1}}{{T}^{-2}}]\]
    (2) Refractive index hole no dimensions.
    (3) Dielectric constant has no dimensions.
    (4) Young's modulus,
    \[Y=\frac{Fl}{A\Delta l}=\frac{[ML{{T}^{-2}}]}{[{{L}^{2}}][L]}=[M{{L}^{-1}}{{T}^{-2}}]\]
    (5) Magnetic field,
    \[B=\frac{F}{Il}=\frac{[ML{{T}^{-2}}]}{[A][L]}=[M{{T}^{-2}}{{A}^{-1}}]\]
    Therefore, option [c] is correct.


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