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Mechanical Engineering · Q85

Heat And Mass Transfer

Engineering and GATE · Mechanical Engineering · question 85

Q85

According to Kirchoff's law, the ratio of emissive power to absorptivity for all bodies is equal to the emissive power of a

A.
Grey body
B.
Brilliant white polished body
C.
Red hot body
D.
Black body
Answer

Answer: Option D

Solution

Answer: Option D
Solution:
Kirchhoff's law states that the emissivity and the absorptivity of a surface at a given temperature and wavelength are equal. The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body.
This statement is known as Kirchhoff's law.