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mediumQ. No. 15145-what-is-the-formula-for-linear-expansion-coefficient

What is the formula for linear expansion coefficient (α)?

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Aα = (increase in length) / (original length × temperature rise)
Bα = (original length) / (increase in length × temperature rise)
Cα = (increase in length × temperature rise) / original length
Dα = (original length × temperature rise) / increase in length
Correct Answer: α = (increase in length) / (original length × temperature rise)Your Answer: A

Explanation

The linear expansion coefficient measures how much a material expands per unit length per degree of temperature rise. Option A is CORRECT — α = ΔL / (L₀ × Δθ), where ΔL is the increase in length, L₀ is the original (initial) length, and Δθ is the temperature rise. Rearranged: ΔL = L₀ × α × Δθ, which gives the actual increase in length. The final length after expansion: L = L₀(1 + αΔθ). Option B is incorrect — placing original length in the numerator and increase in length in the denominator inverts the correct formula. Option C is incorrect — multiplying temperature rise with length increase in the numerator gives wrong dimensions. α is dimensionless per degree, not [length²·temperature/length]. Option D is incorrect — this formula would give units of (length × temperature)/length = temperature, which is not the unit of α.

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