Question

What do you understand by the term thermal expansion?

Answer 1

If you pay attention to the question, it contains the answer. The terms thermal and expansion gives us enough information about what and how to answer this particular question. Thinking more about it might lead to the ways in which a material can change its form when subjected to some amount of heat.

Complete answer:
Thermal expansion is the tendency of matter to change in volume in light of temperature alterations. At the point when a substance is warmed, its particles move more and consequently keep a more noteworthy distance. In easy terms, the expansion of a substance upon the application of heat is called thermal expansion of the substance.

Thermal expansion is of three types depending on how the change in size, shape or volume occurs in materials. These three types of thermal expansion are:
(a) Linear expansion: As the name suggests this happens when the length of the material changes when subjected to heat.The formula for finding linear thermal expansion is given by:
$\dfrac{{\Delta L}}{{{L_0}}} = {\alpha _L}\Delta T$
Where, $\Delta L$ is the change in length, ${L_0}$ is the original length, ${\alpha _L}$ is the coefficient of linear expansion and $\Delta T$ is the change in temperature.

(b) Area expansion: It is exactly as it sounds, the change in the area of the material when it is subjected to a change in temperature.The formula for finding the area expansion is given by:
$\dfrac{{\Delta A}}{{{A_0}}} = {\alpha _A}\Delta T$
Where $\Delta A$ is the change in area, ${A_0}$ is the original area and ${\alpha _A}$ is the coefficient of area expansion.

(c) Volume expansion: It is the change in the volume of the material due to the application of heat.The formula for finding the volume expansion is given by:
$\dfrac{{\Delta V}}{{{V_0}}} = {\alpha _V}\Delta T$
Where, $\Delta V$ is the change in volume of the material, ${V_0}$ is the original volume and ${\alpha _V}$ is the coefficient of volume expansion.

Note: Thermal expansion is often confused with stress, strain etc. stress is when the internal forces acting on neighboring particles exert forces on each other and strain is more similar to thermal expansion because it is the measure of how much an object is deformed or changed when a force is applied. The main difference is, strain occurs when a force is applied and thermal expansion occurs when heat is applied.