Discussion :: Heat and Mass Transfer
- 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. |
C.
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
Explanation :
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.
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