### Theory:

Types of expansion in solids:
Whenever we heat a solid, there is an increase in the dimensions of the body. It is known as expansion in solids.

It undergoes three types of expansions.

1. Linear or Longitudinal expansions
2. Areal or Superficial expansions
3. Cubical or Volumetric expansions

Linear expansions:

When we heat a solid, if there is an increase in the body's length, this is called Linear expansion. It is also known as Longitudinal expansion.

Linear expansion in solid

The increase in the length is proportional to the rise in temperature, original length, and material type.

Areal expansions:

When we heat a solid, if there is an increase in the area of the body, this is called Areal expansion. It is also known as Superficial expansion

Areal expansion in solid

In the case of areal expansion, the change in area is directly proportional to the original area and the change in temperature due to heating.

Cubical expansions:

When we heat a solid, if there is an increase in the volume of the body, this is called Cubical expansion. It is also known as Volumetric expansion.
Cubical expansion in solid

In cubical expansion, due to heating, the change in volume is directly proportional to the original volume and also the change in temperature.