A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors.
Read more about Passive Infrared Sensor: Operating Principles, Construction, PIR-based Motion Detector, PIR-based Remote Thermometer
Famous quotes containing the word passive:
“To make oneself an object, to make oneself passive, is a very different thing from being a passive object.”
—Simone De Beauvoir (1908–1986)