Strålingslovene

Strålingslovene are fundamental principles that describe how electromagnetic radiation is produced, absorbed, and emitted by matter, particularly in thermal equilibrium. They form the theoretical backbone of blackbody radiation and quantum theory, with wide applications in astrophysics, climate science, and engineering. The laws explain how objects at a given temperature radiate energy, and how the spectrum of this radiation depends on temperature and material properties.

Key components include Planck's law, which gives the spectral distribution of a blackbody and introduced quantum concepts; the Stefan-Boltzmann law, which states that the total emitted power scales with the fourth power of temperature; and Wien's displacement law, which relates the peak emission wavelength to temperature. Kirchhoff's law of thermal radiation states that, at thermal equilibrium, the emissivity of a surface equals its absorptivity for each wavelength.

In practice, real objects are not perfect blackbodies; they have wavelength-dependent emissivity, and materials, surfaces, and atmospheres alter the spectrum. The strålingslovene are idealized; they are extended by radiative transfer theory to model propagation through media. They also set the baseline for remote sensing and planetary science.