Associate Safety Professional Practice Exam

What type of smoke detector responds to particles passing through a light beam?

1. Ionization detector

2. Photoelectric detector

3. Thermal detector

4. Manual detector

The correct answer is: Photoelectric detector

A photoelectric detector is designed to respond to particles that interrupt or scatter a light beam. This type of smoke detector operates based on the principle of light scattering, where smoke particles in the air cause a disruption in the light path, triggering the alarm. The sensitivity of photoelectric detectors makes them particularly effective in detecting smoldering fires, which produce larger particles and more smoke before reaching open flames. In contrast, ionization detectors function by using a small amount of radioactive material to create ions in the air, and they are more responsive to the smaller particles produced by fast-burning fires. Thermal detectors rely on temperature changes to activate an alarm and do not directly respond to smoke particles. Manual detectors require human intervention to detect smoke and activate an alarm, which is not an automatic response capability like that of a photoelectric detector. This understanding of how photoelectric smoke detectors utilize light to detect fire hazards is essential in fire safety and residential or commercial safety planning.