# Illustration Thermal expansion of a metallic rod

A metal rod of length $$l_0$$ with initial temperature $$T_0$$ is heated to final temperature $$T_1$$. As a result of the heating, the rod expands to length $$l_1$$. The change in length is:$$\Delta l ~=~ l_1 - l_2$$
The greater the coefficient of thermal expansion $$\alpha$$ of the metal, the more the metal rod expands.