Question 648: Thermodynamics & KTG

Question

For a perfectly black body, coefficient of emission is

Accepted Answer

For a perfectly black body:
By definition
, a black body absorbs all the radiation incident on it.
According to KirchhoffÃ¢ÂÂs law of radiation,
for a body in thermal equilibrium, the ratio of emissive power to absorptive power is the same for all bodies at a given temperature and wavelength
.
Since a black body has
absorptivity = 1
, it also has
emissivity = 1
.
Therefore,
Correct option: B. unity
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Answer

zero.

Answer

unity.

Answer

less than one (non-zero).

Answer

infinity.

Thermodynamics & KTG

For a perfectly black body, coefficient of emission is

Choose the correct answer: