Question

What is the value of coefficient of emission (e) of a perfectly black body?​

Answer 1

Answer:

Real materials emit energy at a fraction—called the emissivity—of black-body energy levels. By definition, a black body in thermal equilibrium has an emissivity ε = 1.

Answer 2

Answer:

Real materials emit energy at a fraction called the emissivity of black-body energy levels. By definition, a black body in thermal equilibrium has an emissivity ε = 1. A source with a lower emissivity, independent of frequency, is often referred to as a gray body. Constructing black bodies with an emissivity as close to 1 as possible remains a topic of current interest.