Black body is an opaque and non reflective body. It absorb wide range of wave lengths. The term black body first introduced by Gustav kirchhoff in 1860. The black body radiation also known as complet radiation or temperature radiation or thermal radiation.
The black body radiation depend only on the temperature of the body known as plank’s spectrum or plank’s law. The temperature of the body increase more than that of 500oc then start to emit significant amount of visible light.
Black body radiation or cavity radiation means an object or system absorbs all the radiation fall on it re-radiates energy which is charecteristics of this radiating system not depend on the type of radiation.
Stefan-Boltzman’s law equation
P= σ AT4
It explains power emited per unit area of the surface a black body is directly praportional to the fourth power of it’s obsolute temperature.
Where P total power radiation per unit area
σ is 5.67X10-8 Wm-2k-4 (Stefan-Boltzman’s constant)
T temperature of the body
A surface area of the body