(N/A) perfect black body is defined as an ideal body that absorbs all the incident electromagnetic radiation of any wavelength falling on it,regardless of the angle of incidence or the frequency of the radiation.
It does not reflect or transmit any radiation.
When heated,a perfect black body emits radiation of all possible wavelengths,which is known as black body radiation.
Examples of a perfect black body include:
$1$. Lampblack: It absorbs about $96\%$ to $98\%$ of the incident radiation.
$2$. Platinum black: It absorbs about $98\%$ of the incident radiation.
$3$. Fery's black body: $A$ practical realization of a perfect black body using a hollow enclosure with a small aperture.