What does the term 'thermal expansion' describe?

The term 'thermal expansion' specifically refers to the increase in volume of a substance due to a rise in temperature. As temperature increases, the particles in a substance gain energy and move more vigorously, causing them to occupy more space. This phenomenon occurs in solids, liquids, and gases, although the degree of expansion and the mechanisms involved can vary among these states of matter.

This concept is critical in engineering and construction, where temperature changes can influence the dimensions of materials and structural integrity. Understanding thermal expansion is essential for safe and effective design, especially in applications like bridges, railways, and other structures that experience significant temperature variations.