Thermal expansion refers to the tendency of a material to expand or contract in response to changes in temperature. When a substance is heated, its molecules gain kinetic energy and vibrate more vigorously. This increased molecular motion causes the substance to expand, resulting in an increase in its dimensions, such as length, area, or volume.
The expansion occurs because the individual molecules move farther apart as they gain energy, which leads to an overall increase in the size of the material. Conversely, when a material is cooled, the decrease in temperature reduces the molecular motion, causing the substance to contract and decrease in size.
Thermal expansion is a property exhibited by most substances, including solids, liquids, and gases. However, the extent of expansion or contraction depends on the specific characteristics of the material. Different materials have different coefficients of thermal expansion, which represent the rate at which they expand or contract per unit change in temperature. It is important to consider thermal expansion in various applications, such as construction, engineering, and the design of structures and components, to account for dimensional changes and prevent potential issues or failures caused by thermal stress.