A photocell can be defined as; it is a light-sensitive module. This can be used by connecting to an electrical or electronic circuit in an extensive range of applications like sunset to sunrise lighting that mechanically turns on whenever intensity of light is low. These are also used in other applications like intruder alarms and also automatic doors.

The photocell is one kind of sensor, which can be used to allow you to sense light. The main features of photo-cell include these are very small, low-power, economical, very simple to use. Because of these reasons, these are used frequently in gadgets, toys, and appliances.

These sensors are frequently referred to as Cadmium-Sulphide (CdS) cells. These are made up of photo resistors and LDRs.

These sensors are apt for light-sensitive applications such as light otherwise dark out. If the block light is there in front of the sensor, if there something disrupting a laser light, sensors which have the majority of light hitting.