The application of the photoelectric effect is everywhere and much

The photoelectric effect is the result of the interaction of light with matter, in which the energy of light is absorbed and an electric current is generated. If, with such exposure to light, the generated electron goes beyond the physical body, then an external photoelectric effect is observed, if it remains inside and causes a change in the conductivity of the material, then the internal one.

The practical application of the photoelectric effect in engineering can be varied. In particular, an external photoelectric effect is used to reproduce sound, for example, in a movie. In addition, special instruments have been created for measuring brightness, light intensity, and illumination. The phenomenon of photoelectric effect is involved in the management of production processes. For this purpose, there are special devices called photocells.

Photocells and their application are based on the fact that the conductivity changes with varying illumination. Basically, such elements are used in control and accounting systems, for example, counting of finished products. Another of their purpose is to control the object's entry into the restricted area. If the press operator's hand enters the work area, the press stops immediately. This is triggered by the photocell. The same device is in the previously mentioned turnstile in the metro: if the payment is made (the photocell is off), then the pass is open, if not (the photocell is on), then it is closed.

The increase of the air pollution also leads to the activation of a photocell signaling a critical situation. The use of photocells in processing machines has made it possible to achieve increased precision in the processing of parts.

Another possibility is to use the photoelectric effect as a current source, or solar cells. In such devices, the work is based on a kind of internal photoelectric effect, called the gate effect. In this case, when light hits a contact between two semiconductors, an EMF occurs, as a result of which a direct conversion of light into electric energy is possible.

Similar solar cells are made on the basis of compounds of gallium arsenide. They allow you to receive electricity without harming the environment - the sun illuminates the surface of the battery, and the output is ready to consume energy. There are no complicated mechanical devices, there is no need to burn fuel or build powerful dams.

However, such an application of the photoelectric effect is currently associated with considerable difficulties. First, the solar cells themselves are expensive and, accordingly, the expensive electricity will be received. Secondly, the efficiency of such a transformation does not exceed 26%. True, work towards increasing efficiency and reducing the cost of converting the light flux continues, and one can hope that soon enough efficient and cheap solar batteries will be ready.

Even now, the need for space stations in electricity is provided by solar batteries. And in places where a lot of sunny days are observed during a year, similar converters work. Prospects for using solar energy are very tempting. Experiments have been carried out to prove that the energy of the sun makes it possible to melt the metal. And if you remember the legend according to which the ancient Greek scientist Archimedes, using mirrors, could burn Roman ships with the help of sunlight, then one can not doubt the unlimited possibilities of using light as an energy source.

In the presented material, the application of the photoelectric effect, the mechanism of its appearance and varieties are considered. Examples of practical use of the photoelectric effect in engineering are given.