Coefficient of linear expansion

Definition

The coefficient of linear expansion is a material property that quantifies the rate at which a material's length changes with temperature. It is typically denoted by the Greek letter $\alpha$ and has units of inverse temperature (e.g., $\text{°C}^{-1}$ or $\text{K}^{-1}$).

5 Must Know Facts For Your Next Test

1. The coefficient of linear expansion, $\alpha$, is defined as $\alpha = \frac{1}{L} \frac{dL}{dT}$, where $L$ is the original length and $dL/dT$ is the rate of change of length with respect to temperature.
2. Different materials have different coefficients of linear expansion; metals generally have higher values compared to ceramics and polymers.
3. In practical applications, the coefficient helps predict thermal stress in structures due to temperature changes.
4. It is crucial for designing objects that will experience varying temperatures to avoid structural damage or failure.
5. Values for the coefficient are often provided in tables for standard materials and can be experimentally determined.

Review Questions

• What does the coefficient of linear expansion measure?
• How is the coefficient of linear expansion mathematically defined?
• Why is it important to consider the coefficient of linear expansion when designing structures?

Related terms

Thermal Expansion: The general increase in volume or length of a material as its temperature increases.

Thermal Stress: Stress induced in a material when it undergoes a change in temperature while being constrained.

$\text{Coefficient of Volume Expansion}$: $\beta$, measures how much a material’s volume changes per degree change in temperature.