What is the difference between black body and a real body?

The spatial radiation intensity of the blackbody is uniform, as opposed to the real body. A blackbody surface completely absorbs external irradiation, regardless of direction and wavelength distribution. Its surface absorptivity is always 1, so αλ = α = 1. The reflectivity of a blackbody is always zero.

What body is considered a black body?

In physics, a black body (in an ideal sense) is an object that absorbs all electromagnetic radiation that falls on it, without any of the radiation passing through it or being reflected by it. Because it does not reflect or transmit visible light, the object appears black when it is cold.

What is a GREY surface?

Gray surface: is a surface which its properties are independent from wavelength. Therefore, the emissivity of a gray, diffuse surface is the total hemispherical (or simply the total) emissivity of that surface. A gray surface should emit as much as radiation as the real surface it represents.

Is the Earth a GREY body?

For example, for the purposes of our model here, we take the varicolored surface of the Earth (on average) as a black body, but it is probably better described as a grey body with a very high emissivity. Note that the temperature of the atmosphere will always be lower than the temperature of the surface.

What is the difference between a black body and a white body?

The name “black body” is given because it absorbs all colors of light. A black body also emits black-body radiation. In contrast, a white body is one with a “rough surface that reflects all incident rays completely and uniformly in all directions.”

What do you mean by perfectly black body?

A body which absorbs all the radiant energy incident upon it and reflects or transmits none is called a perfectly black body. It absorbs all incident energy.

What is the emissivity of a black body?

1
Emissivity is defined as the ratio of the energy radiated from the surface of a material to that radiated from a perfect emitter, known as a blackbody, at the same temperature and wavelength. A blackbody has an emissivity of 1.