A photocell or photoresistor is a sensor that changes its resistance when light shines on it. The resistance generated varies depending on the light striking at his surface. A high intensity of light incident on the surface will cause a lower resistance, whereas a lower intensity of light will cause higher resistance.
The basic characteristics of the photocell were tested and analysed through experiments by an optical control experimental platform, such as short circuit current, open circuit voltage, illumination characteristic, volt ampere characteristic, load characteristic, and spectral characteristic.
3.1. Work Principle and Basic Characteristics of Photocell Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation which are widely used in the digital camera, optical communication, solar cells and other fields, the photocell is a basic unit of semiconductor photoelectric detector.
The sensitivity of photocells can be quoted in either of two ways, either as the electrical output at a given illumination, using illumination figures in units of lux, often 50 lux and 1000 lux, or as a figure of power falling on the cell per square centimetre of sensitive area, a quantity known as irradiance.
Photosensitivity plays a role in a variety of skin diseases but most of the causative mechanisms are still not completely resolved. Ultraviolet (UV) radiation can have both immunosuppressive and inflammatory effects as well as influence antimicrobial peptides, produce reactive oxygen species and induce DNA damage.
Photocells are included in photographic exposure meters, light-and dark-activated lights, and intrusion alarms. Some light-activated alarms are triggered by breaking a light beam. There are even light-reflective smoke alarms based on photocells. Fig. 5 to 20 show practical photocell circuits; each will work with almost any photocell.