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:
“She has taken her passive pigeon poor,
She has buried him down and down.
He never shall sally to Sally
Nor soil any roofs of the town.”
—Gwendolyn Brooks (b. 1917)