lämpölaajenemiskerroimeen

Thermal expansion coefficient is a material property that describes how much a substance expands or contracts in response to changes in temperature. It is a measure of the relative change in size per degree Celsius or Kelvin. Different materials have different thermal expansion coefficients, meaning they expand or contract at different rates. For most substances, expansion occurs as temperature increases, and contraction occurs as temperature decreases. This phenomenon is known as thermal expansion.

The coefficient of thermal expansion is typically denoted by the Greek letter alpha (α). It can be expressed as a linear coefficient (α_l), a superficial (area) coefficient (α_a), or a volumetric (volume) coefficient (α_v). For solids, the linear coefficient is often used, representing the change in length per unit length per degree Celsius. For liquids and gases, the volumetric coefficient is more relevant, describing the change in volume per unit volume per degree Celsius. The relationship between these coefficients depends on the dimensionality of the expansion being considered.

Understanding thermal expansion is crucial in many engineering and scientific applications. For example, it must be accounted for in the design of bridges, buildings, and pipelines to prevent structural damage due to temperature fluctuations. In thermometers, the thermal expansion of a liquid or gas is used to measure temperature. The phenomenon also plays a role in the functioning of thermostats and in the selection of materials for specific operating environments.