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Thermal Expansion

With the increase in temperature of a body, there is an increase in its dimension also. This property is known as thermal expansion. The thermal expansion of a body can be studied as a function of temperature.

One of the common examples of thermal expansion is seen while opening a tight metal jar lid. People often loosen a tight metal jar lid by holding it under hot water. By doing so, the metal of the lid and the glass of the jar, both expand because the hot water adds energy to their atoms. But the metal expands more as compared to glass and gets loosen up.

Types Of Thermal Expansion

Linear expansion

Now let us consider a rod at a temperature T and suppose its length is L at the same temperature. When the temperature is increased to T + ΔT, the length also increases to L + ΔL.



ΔL change in length, L = original length, ΔT = change in temperature, αL = linear coefficient of thermal expansion.

Area expansion


Here, β is the coefficient of surface expansion.

Volume expansion

∆v = Vy∆t

Here y is the coefficient of volume expansion.

Video Lesson – Thermal Expansion

Solved Problem on Thermal Expansion

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Frequently Asked Questions on Thermal Expansion

Define thermal expansion.

The increase in the size of a body due to the increase in the temperature is called thermal expansion.

What is linear expansion?

When a solid is heated and its length increases, then the expansion is called linear expansion.

What is superficial or area expansion?

When a solid is heated and its area increases, then the thermal expansion is called superficial or area expansion.

What is volume or cubical expansion?

When the substance is heated and its volume increases, then the expansion is called volume expansion or cubical expansion.

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