# What is the idea of Thermal Expansion?

Oct 15, 2017

See below.

#### Explanation:

The idea of thermal expansion is that a material can change in shape/area/volume in response to a change in temperature.

There are three general types of thermal expansion: linear, area, and volume.

• Linear  expansion:

$\textcolor{b l u e}{\frac{\Delta L}{L} _ 0 = \alpha \Delta T}$

Where:

• ${L}_{0}$ is the original length of the material
• $\Delta L$ is the change in length (making $\frac{\Delta L}{L} _ 0$ the fractional change in length)
• $\alpha$ is the expansion coefficient (depends on specific material), and
• $\Delta T$ is the temperature change experienced by the material

• Area expansion:

$\textcolor{red}{\frac{\Delta A}{A} _ 0 = 2 \alpha \Delta T}$

• Where $\frac{\Delta A}{A} _ 0$ is the fractional change in area

• Every linear dimension increases by the same percentage with a change in temperature.

• Volume expansion:

$\textcolor{p u r p \le}{\frac{\Delta V}{V} _ 0 = 3 \alpha \Delta T}$

• Where $\frac{\Delta V}{V} _ 0$ is the fractional change in volume