Effect of Temperature on Bodies:

It is a general observation and experience in that the size of a body increases as the temperature increases although it decreases as the temperature decreases. Therefore, temperature rise results in expansion that is increase in linear dimensions of the body, and temperature fall results in contraction, that is reduction in the linear dimensions of the body. The magnitude of a modification brought in linear dimensions of the body through temperature is described by an intrinsic property of the material, of that the body is made of, known as coefficient of linear thermal contraction or expansions.

The coefficient of linear thermal expansion or contraction of a material is described as the change within length per unit length per degree change within temperature of the body that is made of the material. The values of this coefficient, α of a few of the general engineering materials are listed in Table.

From the definition, α could be written as,

α = ΔL/L × 1/ΔT

where, ΔL is the change in length over a total length L while the temperature is changed through ΔT. Therefore,

ΔL = α × L × ΔT

Table