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JEE Main 2019 (9 Jan, Shift 2) · Applications of Dimensional Analysis

Applications of Dimensional Analysis question from JEE Main 2019 (9 Jan, Shift 2)

Q59JEE Main 2019 · 9 JAN · SHIFT 2Easy

Applications of Dimensional Analysis

Expression for time in terms of G (universal gravitational constant), h (Planck constant) and c (speed of light) is proportional to:

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Answer: (c)

  1. [G]=M−1L3T−2[G] = M^{-1}L^3T^{-2}, [h]=ML2T−1[h] = ML^2T^{-1}, [c]=LT−1[c] = LT^{-1}.
  2. [Gh]=L5T−3[Gh] = L^5T^{-3}, and [c5]=L5T−5[c^5] = L^5T^{-5}.
  3. [Ghc5]=T2\left[\dfrac{Gh}{c^5}\right] = T^2, so Ghc5\sqrt{\dfrac{Gh}{c^5}} has dimension of time.
  4. So the answer is (c).
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