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 under such exposure to light the generated electron goes beyond the physical body, then an external photoelectric effect is observed, if it remains inside and leads to a change in the conductivity of the material, then the internal one.
The practical application of the photoelectric effect in technology 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 photoelectric effect is involved in the management of production processes. To do this, there are special devices called photocells.
Photocells and their application are based on the fact of a change in conductivity with a change in illumination. Basically, such elements are used in control and accounting systems, for example, counting finished products. Their other purpose is to control the entry of an object into the restricted area. If the hand of the press operator falls into the working area, then the press immediately stops. This triggers the photocell. The same device is in the above-mentioned turnstile in the subway: if payment has been made (photocell disabled), then the passage is open, if not (photocell enabled), then it is closed.
An increase in the smoke content of the air also triggers a photocell signaling a critical situation. The use of photocells in processing machines made it possible to achieve increased accuracy in processing parts.
Another possibility is to use the photoelectric effect as a current source, or solar panels. In such devices, the work is based on a variation of the internal photoeffect called the valve photoelectric effect. In this case, when light enters the contact of two semiconductors, an EMF occurs, as a result of which direct conversion of light into electrical energy is possible.
Such solar panels are made on the basis of gallium arsenide compounds. They allow you to receive electricity without harming the environment - the sun illuminates the surface of the battery, and the output is ready for consumption energy. There are no complicated mechanical devices; there is no need to burn fuel or build powerful dams.
However, this application of the photoelectric effect is currently fraught with considerable difficulties. Firstly, the solar panels themselves are expensive and, accordingly, the generated electricity will be expensive. Secondly, the efficiency of such a conversion does not exceed 26%. True, work in the direction of increasing efficiency and reducing the cost of converting light flux is ongoing, and it is hoped that fairly efficient and cheap solar panels will be ready soon.
After all, even now, the need for space stations in electricity is provided by solar panels. And in places where there are many sunny days during the year, such converters work. The prospects for using solar energy are very tempting. Experiments have been carried out, proving that the energy of the sun allows melt the metal. And if we recall the legend according to which the ancient Greek scholar Archimedes, using mirrors, was able to burn Roman ships using sunlight, then there is no doubt about the unlimited possibilities of using light as a source of energy.
The presented material discusses the use of the photoelectric effect, the mechanism of its occurrence and variety. Examples of the practical use of the photoelectric effect in technology are given.