When the temperature acts on the body, it undergoes a change in the length, width, height, or volume of the material. Since the atoms are tightly packed in solids, thermal expansion is seen evidently here. In this article, let us know more about thermal expansion and formulas of linear expansion, area expansion, and volume expansion.
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What is Thermal Expansion
Thermal expansion is the phenomenon observed in solids, liquids, and gases. In this process, an object or body expands on the application of heat (temperature). Thermal expansion defines the tendency of an object to change its dimension either in length, density, area, or volume due to heat. When the substance is heated it increases its kinetic energy. Thermal expansion is of three types:
- Linear expansion
- Area expansion
- Volume expansion
The relative expansion of the material divided by the change in temperature is known as the coefficient of linear thermal expansion. The coefficient of linear thermal expansion generally varies with temperature.
Read more:Â Thermal expansion of solids
Linear Expansion
Linear expansion is the change in length due to heat. Linear expansion formula is given as,
Where,
L0 = original length,
L = expanded length,
α = length expansion coefficient,
ΔT = temperature difference,
ΔL = change in length
Volume Expansion
Volume expansion is the change in volume due to temperature. Volume expansion formula is given as
Where,
V0 = original volume,
V = expanded volume,
αv = volume expansion coefficient,
ΔT = temperature difference,
ΔV = change in volume after expansion
Area Expansion
Area expansion occurs is the change in area due to temperature change. Area expansion formula is given as,
Where,
A = original area,
ΔA = change in the area,
αA = area expansion coefficient,
ΔT = temperature difference,
A0 = expanded area.
Solved Examples
Example 1
A rod of length 5 m heated to 40°C. If the length increases to 7 m after some time. Find the expansion coefficient. Room temperature is 30°C.
Solution:
Given:
Initial length Lo = 5 m,
Expanded length L = 7 m
Change in length Δ L = 7 – 5 = 2 m
Temperature difference Δ T = 40°C – 30°C  = 10°C
Absolute temperature T = 10°C +273=283 K
The linear expansion formula is given by,
∴  Length expansion coefficient is given by,
   = 2 / 5 x 283
 Â
See the video below, to have a clear idea about thermal expansion.
Hope you have understood about thermal expansion. Stay tuned with BYJU’S to know about various science and maths concepts.
Frequently Asked Questions – FAQs
What is thermal expansion?
Thermal expansion is the process in which an object or body expands on the application of heat.
Thermal expansion effects which properties of matter?
Thermal expansion effects the shape, volume, area, and density of the body.
What is the coefficient of linear thermal expansion?
The relative expansion of the material divided by the change in temperature is known as the coefficient of linear thermal expansion.
Do all materials have the same expansion coefficients?
No.
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