What is perfectly black body? State its properties.

 A body which can absorb all the radiant heat incident on it is called perfectly black body. Properties: 

1) A perfectly black body absorbs all the quantity of radiant heat incident on it.

2) Coefficient of absorption = 1

3) Coefficient of emission = 1

(i.e.) it is best emitter of heat energy.

4) Coefficient of reflection and transmission = 0