Question

What is a perfect blackbody? with a neatlabelled diagram, "explain ferry's perfectly blackbody.
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Answer 1

A perfect black body is the one which absorbs completely heat radiations of all wavelengths which fall on it and emits heat radiations of all wavelengths when heated. Since a perfect black body neither reflects nor transmits any radiation, the absorptive power of a perfectly black body is unity .

Ferry's perfect blackbody - A cavity with walls made of any material, with a small opening, is an excellent black body. This is Ferry's black body. It also absorbs all electromagnetic radiation incident on it irrespective of wavelength.