Photo effect is the result of interactionlight with a substance in which the light energy is absorbed and an electric current is generated. If, with such exposure to light, the generated electron goes beyond the limits of 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 it is internal.
Practical application of the photo effect in the techniquecan be varied. In particular, an external photo effect is used to reproduce sound, for example, in a movie. In addition, special instruments have been created for measuring brightness, luminous intensity, and illuminance. The phenomenon of the photoelectric effect is involved in the management of production processes. For this there are special devices called photocells.
Photovoltaic cells and their application are based on fact.conductivity changes with changes in light. Basically, such elements are used in control and accounting systems, for example, counting finished products. Their other purpose is to control the object from entering the restricted area. If the hand of the press operator enters the work area, the press immediately stops. This is triggered photocell. The same device is in the previously mentioned turnstile in the subway: if payment is made (photocell is disabled), then the passage is open, if not (photocell is turned on), then it is closed.
Increased air pollution also leads tophotocell signaling of a critical situation. The use of photocells in processing machines allowed us to achieve higher precision machining parts.
Another possibility is to usephoto effect as a current source, or solar panels. In such devices, the work is based on a variation of the internal photoelectric effect, called the valve photoelectric effect. In this case, when light hits the contact of two semiconductors, an emf occurs, as a result of which direct conversion of light into electrical energy is possible.
These solar panels are made onBased on gallium arsenide compounds. They allow you to get 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, this application of the photoelectric effect is associated withpresent with considerable difficulty. Firstly, the solar panels themselves are expensive and, accordingly, the received electric power 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 the luminous flux continues, and it can be hoped that rather efficient and cheap solar batteries will soon be ready.
Even now the need of space stationsin electricity provide solar panels. And in places where there are many sunny days throughout the year, similar converters work. The prospects for the use of solar energy are very attractive. Experiments have been performed that prove that the sun’s energy makes it possible to melt metal. And if we still recall the legend according to which the ancient Greek scientist Archimedes, using mirrors, could burn Roman ships with the help of sunlight, then there is no doubt about the unlimited possibilities of using light as an energy source.
The presented material describes 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.
