What is a Motion Detector?

What is a Motion Detector?

• A. A sensor that detects motion using passive infrared and/or microwave technology, protected by a tamper switch
• B. A camera that records movement
• C. A door contact sensor
• D. A heat detector that triggers on temperature rise

Answer: (A)

Motion detectors identify movement by sensing changes in energy in their surroundings. The typical device uses passive infrared (PIR) sensing to pick up heat patterns within its field of view, and many models also incorporate microwave technology that sends out signals and detects changes in frequency or reflections caused by moving objects. Some units combine both methods to improve reliability and reduce false alarms. A tamper switch is often included to alert you if someone tries to open or disable the detector, adding protection against tampering. This combination—detecting motion with PIR (and sometimes microwave) and including a tamper mechanism—defines a motion detector. A camera records movement, which is why it’s not the device described by the term motion detector. A door contact sensor detects whether a door is opened or closed, not general movement inside a space. A heat detector responds to temperature rise, not movement.

Motion detectors identify movement by sensing changes in energy in their surroundings. The typical device uses passive infrared (PIR) sensing to pick up heat patterns within its field of view, and many models also incorporate microwave technology that sends out signals and detects changes in frequency or reflections caused by moving objects. Some units combine both methods to improve reliability and reduce false alarms. A tamper switch is often included to alert you if someone tries to open or disable the detector, adding protection against tampering. This combination—detecting motion with PIR (and sometimes microwave) and including a tamper mechanism—defines a motion detector.

A camera records movement, which is why it’s not the device described by the term motion detector. A door contact sensor detects whether a door is opened or closed, not general movement inside a space. A heat detector responds to temperature rise, not movement.