What is The Definition Of A Motion Sensor For Light Switch? A motion sensor for light switch is a device that detects movement and then activates a light switch. It is often used to provide convenience in areas of the home or office that require frequent lighting changes or to increase energy efficiency. It typically works by detecting infrared radiation, which is emitted by any moving object, and translating that radiation into an electrical signal. When the signal is detected, the light switch is automatically switched on or off. Motion sensors for light switches can be set to respond to specific levels of movement, duration of movement, and even sensitivity. In addition, they can be programmed to work with different types of lighting fixtures, such as dimmers, timers, and motion-activated floodlights. The motion sensor’s ability to detect motion and activate the lighting switch can make a major difference in energy efficiency and convenience.