lämmönjohtumislain

Lämpöjohtumislaki, also known as Fourier's law of heat conduction, is a fundamental physical law that describes the rate of heat transfer through a material. It states that the heat flux through a material is proportional to the negative temperature gradient. In simpler terms, heat flows from hotter regions to colder regions, and the rate of this flow is determined by how quickly the temperature changes over a distance and the thermal conductivity of the material.

The law can be expressed mathematically. The one-dimensional form states that the rate of heat transfer per unit area (heat flux, q) is equal to the negative of the thermal conductivity (k) multiplied by the temperature gradient (dT/dx). The negative sign indicates that heat flow is in the direction of decreasing temperature. Thermal conductivity is a material property that quantifies how well a substance conducts heat. Materials with high thermal conductivity, like metals, transfer heat quickly, while materials with low thermal conductivity, like insulators, transfer heat slowly.

Fourier's law is crucial in various engineering and scientific fields, including thermodynamics, heat transfer analysis, and material science. It is used to design insulation, heat exchangers, and to understand thermal behavior in a wide range of applications, from electronics to building design. While the original law applies to steady-state conditions, it can be extended to analyze transient heat transfer as well.