Relation Between Expansion Coefficients (αv = 3αl and αa = 2αl)
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αv = 3αl and αa = 2αl
What each symbol means
| Symbol | What it stands for |
|---|---|
| αa | Coefficient of area (superficial) expansion (K⁻¹) |
| αl | Coefficient of linear expansion (K⁻¹) |
| αv | Coefficient of volume (cubical) expansion (K⁻¹) |
When to use this
Derived for isotropic materials from (1+αl ΔT)³ ≈ 1+3αl ΔT for small αl ΔT. ΔA/A = αa ΔT, ΔV/V = αv ΔT. For ideal gas at constant pressure, αv = 1/T. Water shows anomalous expansion: contracts from 0°C to 4°C, then expands normally.