Photocell


Photocell
The photocell (light cell) is a craft technological application of the photoelectric effect. The photocell is a device that converts light energy into electrical energy. It is sometimes called the electric eye. A photocell consists of a semi-cylindrical light-sensitive metal plate C (emitter) and a wire loop (loop) A (collector) mounted in a vacuum glass or quartz bulb.
An external circuit, as shown in this diagram, is coupled to a high-voltage battery B and micrometer (μA), sometimes in place of plaque C, a thin layer of light-sensitive material (C) in the inner core of the bulb. Is affixed to the surface. One part of the bulb is left clean so that light can enter it.

Electrons are emitted when the light of the appropriate wavelength falls on the emitter C. They are attracted to the optical electron collector. A certain optical stream of some micrometer is obtained from a light cell.
Electrons are emitted when the light of the appropriate wavelength falls on the emitter C. They are attracted to the optical electron collector. The optical current of a few microamperes is obtained from a light cell. A light cell can change the optical current by changing the light intensity. This current can be used in the conduction and light measurement devices of the control apparatus. Light cells of sensitized lead sulfide for infrared radiation are used in electronic ignition circuits. 

In scientific works, light cells are used in all applications to measure light intensity. Light measurements in photography cameras use the light cell to measure the intensity of incident light. The light cell in an automatic door controller is used in a door-light electrical circuit. Moving towards the door, the light beam on the light cell can be obstructed by the person. A sudden change in the optical current can be used to start the motor to open a door or to sound an alarm. They are also used under the control of a counting device that identifies each block of the light beam that is caused by a person or object moving across the beam. 

Therefore, the light cell helps in calculating the number of persons entering an auditorium if they enter the vast room one by one. They are used to identify traffic rule breakers. An alarm can be played whenever a beam of radiation is blocked. In Chor Alarm, ultraviolet light (invisible) is applied to the light cell installed at the saint entrance. A person who enters the door blocks the beam of light falling on the light cell. The use of a sudden change in the illuminating current is initiated by the ringing of an electric bell. In fire-alarm, several light cells are installed at appropriate places in the building. Light radiation falls on the light cell when a fire occurs. 

This completes the circuit through an electric bell or a horn and starts functioning as a warning signal. 
Lighting cells are used for the reproduction of sound in mobile imagery and scanning and visual broadcasting in television cameras. They are also used in industries to find small errors and holes in metal sheets.