Q63
Which of the following statement is correct?
A.
A grey body is one which absorbs all radiations incident on it.
B.
At thermal equilibrium, the emissivity and absorptivity are same.
AnswerC.
The energy absorbed by a body to the total energy falling on it, is called emissivity.
D.
A perfect body is one which is black in colour.
Answer: Option B
Solution
Answer: Option B
Solution:
A blackbody allows all incident radiation to pass into it (no reflected energy) and internally absorbs all the incident radiation (no energy transmitted through the body).
Absorptive power is a measure of heat absorbed by an object. When heat is incident on the surface an object, a part of it is absorbed and the remaining part is reflected. Usually the absorbed radiation is converted to thermal energy, increasing the object's temperature.