lämpöjohtokyvyllisyys

Lämpöjohtokyvyllisyys, often referred to as thermal conductivity in English, is a fundamental physical property of a material that describes its ability to conduct heat. It quantifies how effectively heat energy is transferred through a material via molecular collisions and electron movement. Materials with high thermal conductivity allow heat to pass through them easily, while materials with low thermal conductivity act as thermal insulators, resisting heat flow.

The unit of thermal conductivity in the International System of Units (SI) is watts per meter-kelvin (W/(m·K)). This unit indicates the amount of heat energy transferred per unit time through a unit area of a material with a unit thickness, when there is a unit temperature difference across that thickness. For example, a material with a thermal conductivity of 100 W/(m·K) will transfer 100 watts of heat through a 1-square-meter area of 1-meter thick material if the temperature difference between its sides is 1 Kelvin.

Thermal conductivity varies significantly depending on the material. Metals, such as copper and aluminum, generally have very high thermal conductivity due to the free movement of electrons. Conversely, non-metals like wood, plastic, and gases typically exhibit low thermal conductivity. This property is crucial in many engineering applications, from designing efficient heat sinks for electronics to insulating buildings to minimize energy loss. Temperature also influences thermal conductivity; for most solids, it decreases with increasing temperature, while for gases, it generally increases.