Thermal radiation

Thermal radiation (radiation) is the transfer of thermal energy, represented by electromagnetic waves, from one body to another. It arises from the internal energy of a given body. The wavelength ranges from 0.74 to 1000 micrometers. Waves that have a certain length are absorbed by the body and then pass through the atmosphere. It is interesting that radiation can occur not only in a certain environment, but also in a vacuum. This process produces heat - a unit of energy.

Thermal radiation can occur due to chemical or nuclear reactions, electromagnetic scattering, as well as mechanical impact on the object. In this case, the energy that is released can be transmitted by touching, that is, the interaction between objects with high and low temperatures, and also by transport with the help of liquids or gases, or radiation (heat transfer from source to matter). The latter method is sufficiently productive to produce heat. Heat rays transfer energy and when they hit the object, this energy is absorbed - and the objects are heated. When two objects with different temperatures come into contact with one another, a heat flow is formed, which stops when the body temperatures are compared. Thus, thermal radiation occurs. This process can take place in nature, for example, in the atmosphere, and artificially, for example, in an incandescent lamp.

It should be noted that each body reproduces continuous radiation and absorbs radiation from other bodies. In the case where there is thermal equilibrium, for each object the flux of radiated and absorbed radiation will be the same. In this case, one can speak of the absence of heat exchange processes between the elements. When the temperature of one element is higher than that of the other, the former will emit more heat energy than absorb it from another body. Here we can talk about the presence of heat exchange between the elements.

Let us consider what is the thermal radiation and its characteristics.

It is known that the elements that are heated to a high temperature, glow. This phenomenon is called thermal radiation. It is made by the motion of molecules of matter having a temperature above zero. Thus, at a high temperature, short visible waves are emitted, at low temperatures, long infrared waves are emitted.

Let's consider the given phenomenon on an example. So, the living quarters are in most cases heated by electric radiators of heat. In this case, the red glow of the spirals is also thermal visible radiation. And infrared radiation carries heat, which warms this room.

Thermal radiation is a kind of radiation that is equilibrium, that is, does not change the macroscopic parameters. All other types of radiation are nonequilibrium.

The essence of all rays is the same. It is represented in the form of propagating electromagnetic waves in space. Thermal energy is formed as a result of the generation of the internal energy of the heated element. In this case, the amount of this kind of energy depends on the temperature and physical properties of the body, which radiates it.

Thermal radiation plays an important role in the natural processes and life activity of a person. The sun is the strongest thermal radiator. The intensity of thermal radiation is approximately 1.3 W / m2.

Thus, in thermodynamic equilibrium, all elements of the system have the same temperature. The energy of thermal radiation that emanates from each body is compensated for by the energy absorbed by this body. Such a process is called equilibrium thermal radiation.