What is coefficient of linear expansion?

When a solid is heated, it increases in volume. It increases in length, breadth, and thickness. The increase in length of any side of a solid will depend on the original length l0, the rise in temperature t, and the coefficient of linear expansion α.

The coefficient of linear expansion may be defined as the increase in length per unit length when the temperature is raised 1°C. Thus if the temperature of a rod of length l0 is raised from 0°C to t°C, the new length, lt, will be given by

(21.1)

The value of the coefficient of expansion varies from substance to substance. The coefficients of linear expansion of some common materials are given in Table 21.1.

references:

https://www.sciencedirect.com/topics/engineering/linear-coefficient-of-expansion#:~:text=The%20coefficient%20of%20linear%20expansion%20may%20be%20defined%20as%20the,is%20raised%201%C2%B0C.