In my book , it is given a statement that "Good Absorbers are Bad Reflectors" and it considerd reflection, absorption and transmission but in some other book it is given that "Good Absorbers are Good Emitter". My question is that which statement is correct ?
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3 Answers
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Both are correct.
According to Kirchhoff's law of thermal radiation, for total heat radiation, the ratio of emissive power to absorptive ratio was the same for all bodies emitting and absorbing thermal radiation in thermodynamic equilibrium.
Thus, this would mean that a good emitter is a good absorber. Naturally, a good absorber is a poor reflector.
answered Aug 22, 2018 at 9:59
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It may be that one statement is more about the visible spectrum and the other statement is more about thermal/black body radiation.
There are maybe/probably some rare materials that do reflect visible but at the same time emit lots of IR ....these statements are guidelines.
answered Aug 22, 2018 at 13:30
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According to me, good absorbers are bad reflectors but they can radiate more energy. So they are good emitters.
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1$\begingroup$ This answer isn't incorrect, but the wording is pretty confusing. $\endgroup$– rob ♦Commented Aug 29, 2018 at 19:49