ESA Certified Alarm Technician Practice Exam

A passive infrared sensor primarily detects patterns of what type of energy?

1. Electric energy

2. Radiating energy

3. Mechanical energy

4. Heat energy

The correct answer is: Radiating energy

A passive infrared (PIR) sensor is designed to detect infrared radiation, which is a form of heat energy emitted by objects based on their temperature. As living beings and warm objects radiate infrared radiation, the PIR sensor picks up changes in infrared levels across its field of view. This ability to detect variations in heat energy allows the sensor to identify the presence of people or animals. By reacting to the thermal patterns, the PIR sensor can trigger alarms or other responses in security systems. While the terms "electric," "mechanical," and "radiating" energy might relate to various forms of physical phenomena, they do not specifically describe the operational principle of a PIR sensor. The essence of a PIR sensor is its sensitivity to heat energy emitted by objects, making this a fundamental aspect of how it functions in security systems.