Längsausdehnung

Längsausdehnung, also known as linear thermal expansion, describes the change in length of a solid material when its temperature changes. This phenomenon is a fundamental property of matter and is directly related to the kinetic energy of the atoms within the material. As temperature increases, atoms vibrate more vigorously, leading to a greater average separation between them, thus causing the material to expand. Conversely, a decrease in temperature reduces atomic vibration, resulting in contraction.

The amount of expansion or contraction is quantified by the coefficient of linear thermal expansion, denoted by the Greek letter alpha (α). This coefficient is a material-specific property and indicates how much a material will expand or contract per degree Celsius (or Fahrenheit) change in temperature. The formula for linear thermal expansion is ΔL = α * L₀ * ΔT, where ΔL is the change in length, α is the coefficient of linear thermal expansion, L₀ is the original length, and ΔT is the change in temperature.

Different materials exhibit different coefficients of linear thermal expansion. For instance, metals generally expand more than ceramics or glass for the same temperature change. This property is crucial in engineering and construction. Engineers must account for thermal expansion in bridges, buildings, and machinery to prevent stress and damage caused by temperature fluctuations. Expansion joints are commonly used in structures to accommodate these changes. In contrast, materials with very low coefficients of thermal expansion, such as Invar, are used in applications requiring high dimensional stability over a range of temperatures, like precision instruments.