Expansion of Solids
Key Concepts
- Introduction
- Linear expansion
- Areal expansion
- Volumetric expansion
Explanation
Introduction:
In this session, we will learn about the effect of heat, particularly on the solids.
Solids show three types of expansions when exposed to heat, they are:
- Linear expansion
- Areal expansion
- Volumetric expansion
Linear expansion:
Let us consider an iron rod of length L1 at temperature T1. When the iron rod is subjected to constant heat, it expands, and its length changes from L1 to L2 and the temperature to T2.
The coefficient of linear expansion is given by:

Where,
α = Coefficient of linear expansion
L1 = Length of the iron rod before heating
L2 = Length of the rod after heating
T1 = Initial temperature of the rod
T2 = Final temperature of the rod after expansion
Points to be remembered:
- Linear expansion is only affecting the length.
- It has only one dimension (Length).
- The coefficient of linear expansion is only one dimensional.
Areal expansion:
Let us consider an iron sheet of area A1 at temperature T1, and the iron sheet is heated constantly. After some time, the area of the iron sheet changes from A1 to A2 at temperature T2.
Then the coefficient of areal expansion is given by:

Where,
β = Coefficient of areal expansion
A1 = Area of the iron sheet before heating
A2 = Area of the iron rod after heating
T1 = Initial temperature of the sheet
T2 = Final temperature of the sheet after expansion
Points to be remembered:
- Areal expansion is only on the area.
- It has two-dimensions (Area).
- The coefficient of areal expansion is only two dimensional.
Volumetric expansion:
Let us consider an iron block with the volume V1 at the temperature T1, and the block is heated constantly. If the volume of the block is changed from V1 to V2 at the temperature T2,
then the coefficient of volumetric expansion is given by:

Where,
γ = Coefficient of volumetric expansion
A1 = Volume of the iron block before heating
A2 = Volume of iron block after heating
T1 = Initial temperature of the block
T2 = Final temperature of the block after expansion
Points to be remembered:
- Volumetric expansion is only on the volume.
- It has a three-dimensions (volume).
- The coefficient of areal expansion is three dimensional
Summary
Solids show three types of expansions when exposed to heat, they are:
- Linear expansion
- Areal expansion
- Volumetric expansion
The coefficient of linear expansion is given by:

Then the coefficient of areal expansion is given by

Then the coefficient of volumetric expansion is given by:

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