Question

Explain fery's concept of a perfect black body

Answer 1

A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. A white body is one with a "rough surface reflects all incident rays completely and uniformly in all directions.A black body in thermal equilibrium  emits electromagnetic radiation called black-body radiation. The radiation is emitted according to Planck's law, meaning that it has a spectrum that is determined by the temperature alone not by the body's shape or composition.