Class NEET 2026 ALL Q #1939
COMPETENCY BASED
APPLY
4 Marks 2026 NTA-RE-NEET-2026 MCQ SINGLE
Consider that $\sigma_{S}$, $k_{B}$, b represents Stefan-Boltzmann constant, Boltzmann constant and Wien's displacement law constant, respectively. The dimension of $\sigma_{s}k_{B}^{-1}b$ is
(A) $[L^{-1}T^{-1}K^{-4}]$
(B) $[L^{-1}T^{-1}K^{-2}]$
(C) $[L^{-1}K^{-2}]$
(D) $[L^{-1}T^{-1}K^{-3}]$
Correct Answer: B

AI Tutor Explanation

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Detailed Solution

Step 1: Identify dimensions of constants

The Stefan-Boltzmann constant $\sigma_{S}$ has dimensions $[M T^{-3} K^{-4}]$. The Boltzmann constant $k_{B}$ has dimensions $[M L^2 T^{-2} K^{-1}]$. The Wien's displacement law constant $b$ has dimensions $[L K]$.

Step 2: Set up the dimensional expression

We need to find the dimensions of the product $\sigma_{S} \cdot k_{B}^{-1} \cdot b$. Substituting the dimensions:

$$[Dimension] = [M T^{-3} K^{-4}] \cdot [M L^2 T^{-2} K^{-1}]^{-1} \cdot [L K]$$

Step 3: Simplify the expression

First, invert the dimensions of $k_{B}$:

$$[k_{B}^{-1}] = [M^{-1} L^{-2} T^2 K^1]$$

Now multiply all terms:

$$[Dimension] = [M T^{-3} K^{-4}] \cdot [M^{-1} L^{-2} T^2 K^1] \cdot [L K]$$ $$[Dimension] = [M^{1-1}] \cdot [L^{-2+1}] \cdot [T^{-3+2}] \cdot [K^{-4+1+1}]$$ $$[Dimension] = [M^0] \cdot [L^{-1}] \cdot [T^{-1}] \cdot [K^{-2}]$$

Final Answer: [L^{-1}T^{-1}K^{-2}]

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Pedagogical Audit
Bloom's Analysis: This is an APPLY question because it requires the student to recall fundamental physical constants and apply dimensional analysis rules to derive a new composite dimension.
Knowledge Dimension: PROCEDURAL
Justification: The student must follow a specific algorithmic process of dimensional substitution and algebraic simplification to reach the result.
Syllabus Audit: In the context of NEET, this is classified as COMPETENCY. This tests the student's ability to manipulate physical quantities, a core skill required for the Units and Measurements chapter in the NEET physics syllabus.