Thermal radiation
All material at a temperature above absolute zero emits electromagnetic radiation because of the thermal motion of the atoms. Thermal radiation has a continuous spectrum which is defined as a function of the temperature and the emissivity of the radiating material.
In lighting technology, the temperature of light sources is expressed on the Absolute Temperature scale (the unit of measurement is the "Kelvin" [K]). Infra-red radiation increases disproportionally with temperature; as the temperature rises, maximum radiation shifts towards shorter wavelengths (Wien's displacement law).
The spectral emissivity of a material is determined by its coefficient of emission e, which is a function of the wavelength and the temperature. It indicates the relationship between this material and an ideal black body radiator.
The coefficient of emission of the metal tungsten, which is used for the filaments in incandescent lamps and tungsten halogen lamps, has the advantage that its peak radiation can be within the visible spectrum.
All material at a temperature above absolute zero emits electromagnetic radiation because of the thermal motion of the atoms. Thermal radiation has a continuous spectrum which is defined as a function of the temperature and the emissivity of the radiating material.
In lighting technology, the temperature of light sources is expressed on the Absolute Temperature scale (the unit of measurement is the "Kelvin" [K]). Infra-red radiation increases disproportionally with temperature; as the temperature rises, maximum radiation shifts towards shorter wavelengths (Wien's displacement law).
The spectral emissivity of a material is determined by its coefficient of emission e, which is a function of the wavelength and the temperature. It indicates the relationship between this material and an ideal black body radiator.
The coefficient of emission of the metal tungsten, which is used for the filaments in incandescent lamps and tungsten halogen lamps, has the advantage that its peak radiation can be within the visible spectrum.