Last Updated:
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). The unit of α is per degree Celsius (°C⁻¹) or per Kelvin (K⁻¹). Different materials have very different values of α. For example, steel ≈ 12 × 10⁻⁶/°C, aluminium ≈ 24 × 10⁻⁶/°C, glass ≈ 9 × 10⁻⁶/°C. 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. For exams: α = ΔL/(L₀·Δθ).
FAQ
Common questions and clear answers for this topic.
Heat is a form of energy that transfers between objects or systems due to a temperature difference, moving from a hotter body to a cooler one until thermal equilibrium is reached.
Practice 5000+ GK Questions with detailed explanation.
Start Practicing Now