The emission of radiation of a non-reflecting ideal black surface is defined by Planck's radiation law. It states that the emitted radiation power increases with increasing temperature and that the maximum of the radiated spectrum is shifted towards shorter wavelengths with rising temperature. The location (wavelength) of the maximum is described by Wien's displacement law which states that there is an inverse relationship between the temperature of a blackbody and the wavelength of the peak emission.

You can immediately see this effect when comparing the light of two electric light bulbs of 50 W power each with the light of a single 100 W bulb. Though both settings require the same electric power, the single 100 W bulb emits brighter light than the two 50 W bulbs (because the temperature of 100 W filament is higher than that of a 50 W bulb).

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English version	[250 kB]
German version	[251 kB]
After downloading please unpack all files of the zipped packages and start the executable.

The program BlackBody shows this radiation effect. The user can take several snapshots of the radiation spectrum in order to compare the effect at different temperatures. For downloading the program click the little floppy disk at right.