Question

What percentage of incident radiation do black surfaces absorb?

Answer 1

Hint: A black body, sometimes known as a black body, is an idealised physical body that absorbs all incident electromagnetic radiation, independent of frequency or incidence angle. Because it absorbs all hues of light, it's given the moniker "black body." Black-body radiation is produced by a black body. A white body, on the other hand, has a "rough surface that fully and evenly reflects all incident rays in all directions.

Complete step by step solution:
Electromagnetic black-body radiation is emitted by a black body in thermal equilibrium (that is, at a constant temperature). The radiation follows Planck's law, which means that its spectrum is controlled only by the temperature (see picture at right), not by the shape or composition of the substance.
There are two significant features of an ideal black substance in thermal equilibrium.
It is an ideal emitter: it emits as much or more thermal radiative energy than any other body at the same temperature at every frequency.
It is a diffuse emitter, meaning that the energy is emitted isotropically, regardless of direction, per unit area perpendicular to the direction.
A black body is a surface that absorbs all radiant energy that falls on it. Because the visible light that strikes the surface is absorbed rather than reflected, the surface appears dark. A tiny hole in a box with a darkened inside is the finest practical illustration of a blackbody. The electromagnetic radiation emitted by a blackbody in thermal equilibrium is known as black body radiation. The spectrum of the radiated radiation is defined only by the temperature, not by the form or content of the substance. A blackbody absorbs 98 percent of the incoming radiation. Polished metal surfaces, on the other hand, absorb only approximately 6% of incoming radiation and reflect the remainder.

Note:
A hole in the wall of a big insulated container is an approximate manifestation of a black surface (an oven, for example). Any light that enters the hole is reflected or absorbed by the body's interior surfaces and is unlikely to re-emerge, making it a near-perfect absorber. When the radiation trapped in such an enclosure reaches thermal equilibrium, the radiation discharged from the hole is the same as that emitted by any other body at that temperature.