Heat and temperature _______________________________________________________________________________________________________________________________________________________________________________________________________________________ 10. Thermal expansion in solids and liquids
The table shows the values of the coefficient of linear expansion for different substances, which may have units of 1/˚C or 1/K.In a solid or a liquid, unlike in a gas, the atoms or molecules are closely packed together, but their kinetic energy (in the form of small, rapid vibrations in solids, also translations in liquids) pushes neighbouring atoms or molecules apart from each other.
This neighbour-to-neighbour pushing results in a slightly greater distance, on average, between neighbours.
For most substances under ordinary conditions, there is no preferred direction, and an increase in temperature will increase the body´s size by a certain fraction in each dimension.
Not all substances expand in the same way, some expand more than others. The change in length L is proportional to length L.
The dependence of thermal expansion on temperature, substance, and length is summarized in the equation: