AIIMS2018Physics-Dimensional Analysis

AIIMS 2018 Physics Dimensional Formula MCQ Question

Type: MCQ-conceptual-Medium-Class 11

Let the expression of velocity is v = kλᵃρᵇgᶜ. Substitute dimensional formula, [M⁰LT⁻¹] = Lᵃ [ML⁻³]ᵇ [LT⁻²]ᶜ = [MᵇLᵃ⁻³ᵇ⁺ᶜT⁻²ᶜ]. Compare powers of the both sides, b = 0, -2c = -1 ⇒ c = 1/2, a - 3b + c = 1 ⇒ a = 1/2. Thus, v ∝ λ¹/²ρ⁰g¹/², v² ∝ λg.

A

v² ∝ λg

B

v² ∝ λ²g

C

v² ∝ λg²

D

v² ∝ λ²g²

Correct Answer

Option B

Detailed Explanation

The expression derived from the dimensional analysis shows that v2λgv^2 \propto \lambda g, indicating that velocity squared is directly proportional to the product of wavelength λ\lambda and gravitational acceleration gg. Option B, v2λ2gv^2 \propto \lambda^2 g, is incorrect because it suggests an additional power of λ\lambda that does not align with the derived relationship. Other options also misrepresent the proportionality by either altering the powers of gg or λ\lambda incorrectly, failing to satisfy the dimensional consistency established in the analysis. Thus, the correct relationship emphasizes the direct proportionality between v2v^2, λ\lambda, and gg as v2λgv^2 \propto \lambda g.

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