Explanation:
If the object is perfectly black then it does not reflect any light. Black body absorbs all incident electromagnetic radiations. The light that comes from the black body is called black body radiation.
The black body spectrum depends on the temperature of object. It emits more black body energy at all wavelength as the temperature of an object increases.
If the black body is heated then it emits the radiation of different wavelength or frequency.
The following is the explanation of the black body radiator by using Planck's quantum theory:
The energy is absorbed or emitted by the black body in the form of small discrete packets of energy. These packets of energies are called the quantum. The quantum of energy is called photon.
The energy of the quantum is directly proportional to the frequency of the radiation. The relation is as follows,
Here, n is the number of photons, h is the Planck's constant and 
is the frequency.
