ESA Certified Alarm Technician Practice Exam

Which list accurately describes the four basic parts of a PIR?

1. Lens, motion sensor, microcontroller, alarm circuitry

2. Optics, infrared transducer, electronic amplifier, signal processing circuitry

3. Microphone, amplifier, transformer, speaker

4. Sensor, processor, output, input

The correct answer is: Optics, infrared transducer, electronic amplifier, signal processing circuitry

The selection of the option that includes optics, infrared transducer, electronic amplifier, and signal processing circuitry accurately reflects the four basic parts of a passive infrared sensor (PIR). Optics are crucial for focusing and directing the incident infrared radiation onto the infrared transducer, which senses changes in infrared levels, typically from warm bodies like humans or pets. The electronic amplifier is essential as it boosts the weak signal produced by the infrared transducer, allowing for adequate detection and processing of the signal. Finally, the signal processing circuitry interprets the amplified signal to determine whether a significant change has occurred, which would indicate motion. This combination of components is fundamental to how PIR sensors operate, allowing them to effectively monitor and detect movement based on infrared emissions. Other options lack elements directly associated with the operational structure of a PIR and include components unrelated to this specific sensor technology.