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Question:
What is a "Blackbody" in terms of Blackbody radiation, the Compton Effect, etc? Thanks.



Replies:
I do not think the Compton effect has anything to do with black bodies - you may be reading about Compton radiation and black body radiation in some context in astronomy though? A "blackbody" is a perfect absorber and radiator (it turns out absorption and radiation are intimately connected) - for example the ... well there are no exact examples... Anyway, the radiation from a blackbody was calculated early in this century and it depends only on the temperature of the body (and the surface area from which the radiation is coming) - the electromagnetic energy radiated has a peak at a frequency that increases as the temperature increases, and the total amount of energy radiated goes as the fourth power of the temperature. When something is very hot, it glows at visible wavelengths (a few thousand degrees) or even ultraviolet light (tens of thousands of degrees) or X-rays (even hotter...) but ordinary objects do not quite match the black body spectrum because of characteristic features in their absorption. Compton radiation comes when electrons are diverted by coming close to atomic nuclei and send of bursts of light.

Arthur Smith



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