Thermal expansion

Definition

Thermal expansion is the increase in volume of a substance due to an increase in temperature. This occurs because particles move more and spread apart as they gain thermal energy.

5 Must Know Facts For Your Next Test

1. Thermal expansion coefficients vary by material, with metals generally having higher coefficients than ceramics.
2. Linear thermal expansion can be described by the equation $\Delta L = \alpha L_0 \Delta T$, where $\alpha$ is the linear expansion coefficient.
3. Volumetric thermal expansion is significant for gases and can be estimated using $\Delta V = \beta V_0 \Delta T$, where $\beta$ is the volumetric expansion coefficient.
4. Bimetallic strips utilize differing thermal expansion properties of metals for practical applications like thermostats.
5. Temperature changes causing thermal expansion can lead to structural stress if not properly accounted for in engineering designs.

Review Questions

• What is the primary cause of thermal expansion?
• Write the formula for linear thermal expansion and define each term.
• How do bimetallic strips make use of different materials' thermal expansion properties?

Related terms

Coefficient of Linear Expansion:

A material-specific constant ($\alpha$) that quantifies how much a material's length changes per degree change in temperature.

Coefficient of Volumetric Expansion: $\beta$ represents how much a material's volume changes per degree change in temperature.

Bimetallic Strip:

A device made from two bonded metals with different coefficients of thermal expansion, which bends when heated or cooled.