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Any object with temperature T > 0 emits EM waves ( radiation )
at all wavelengths.
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If the object is a perfect absorber, it will not
reflect any light. Call this a blackbody.
- A perfect absorber re-emits all light incident
on it.
- The emitted light has a special spectrum
called a blackbody spectrum.
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Spectrum is the intensity of the line as the function of
wavelength
- Blackbody spectrum is continous and
only depends on the surface temperature of the object.
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The Sun radiation is almost blackbody
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