Which term describes the property that relates length change to temperature for solids?

• A. Linear expansion coefficient
• B. Thermal conductivity
• C. Specific heat
• D. Bulk modulus

Answer: (B)

When solids are heated, their dimensions tend to grow. The quantity that quantifies how much a material’s length changes per degree of temperature change is the coefficient of linear thermal expansion, usually written as α. It links the change in length to the original length and the temperature change through ΔL ≈ α L0 ΔT, so the fractional change is ΔL/L0 = α ΔT. For isotropic materials, if you consider volume, the volumetric expansion coefficient β is about three times α (β ≈ 3α). This concept is distinct from other properties: thermal conductivity describes how quickly heat flows, specific heat is about energy required to raise temperature, and bulk modulus relates to how compressible a material is under pressure. So the term describing length change with temperature for solids is the coefficient of linear thermal expansion.