Remember - for thermal radiation - the frequency of light (the energy of each photon) is proportional to the
temperature of the
emitter:
Human body = 300
K Þ 10 microns,
or 100,000 Å (infrared)
Sun, light bulb
filament = 6000 K Þ 5000
Å (visible, yellow)
Hot star’s surface = 40,000 K Þ 750 Å (far ultraviolet)
Really hot plasma = 5,000,000
K Þ 6 Å
(X-ray)
*don’t forget that thermal emitters give off photons
with a range of wavelengths; those listed above represent the peak of the
distribution