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JEE Main 2019 (11 Jan, Shift 1) · Applications of Dimensional Analysis

Applications of Dimensional Analysis question from JEE Main 2019 (11 Jan, Shift 1)

Q60JEE Main 2019 · 11 JAN · SHIFT 1Medium

Applications of Dimensional Analysis

The force of interaction between two atoms is given by F = αβ\alpha\betaexp (−x2αkT)\left(-\frac{x^2}{\alpha kT}\right); where x is the distance, k is the Boltzmann constant and T is temperature and α\alpha and β\beta are two constants. The dimension of β\beta is:

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Answer: (b)

  1. Exponent is dimensionless: [α]=L2ML2T−2=M−1T2[\alpha] = \dfrac{L^2}{ML^2T^{-2}} = M^{-1}T^2.
  2. [F]=[α][β][F] = [\alpha][\beta], so [β]=MLT−2M−1T2[\beta] = \dfrac{MLT^{-2}}{M^{-1}T^2}.
  3. [β]=M2LT−4[\beta] = M^2LT^{-4}, so the answer is (b).
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