Lämpöjohtuma

Lämpöjohtuma, also known as thermal conduction, is a fundamental mode of heat transfer. It describes the transfer of thermal energy through direct contact between particles within a substance or between different substances in contact. This process occurs when there is a temperature difference, with heat flowing from a region of higher temperature to a region of lower temperature.

In solids, thermal energy is transferred primarily through vibrations of the lattice structure and, in conductive materials like metals, through the movement of free electrons. When one part of a solid is heated, its atoms vibrate more vigorously. These vibrations are passed on to neighboring atoms through interatomic forces, propagating the thermal energy through the material. The efficiency of this transfer depends on the material's thermal conductivity. Materials with high thermal conductivity, such as metals, allow heat to pass through them easily, while materials with low thermal conductivity, like insulators (e.g., wood, plastic), resist heat flow.

In fluids (liquids and gases), conduction also occurs due to particle collisions. Hotter, more energetic particles collide with cooler, less energetic particles, transferring kinetic energy. However, in fluids, convection, which involves the bulk movement of the fluid itself, is often a more significant mode of heat transfer, especially when there are density differences caused by temperature variations. Lämpöjohtuma is a crucial concept in many scientific and engineering applications, influencing everything from the design of heat sinks in electronics to the insulation of buildings.