Certified Safety Professional Exam 2025 – 400 Free Practice Questions to Pass the Exam

In light scattering detectors, the alarm is triggered when light is reflected from smoke particles onto a sensor. This principle works on the basis that when light, such as from a laser or LED, passes through the air and encounters smoke, the particles in the smoke scatter the light. The scattered light then reflects towards a photodetector or sensor, which is designed to detect changes in light intensity.

When the concentration of smoke particles in the air increases, more light is scattered, leading to a significant increase in the signal detected by the sensor. When this signal exceeds a predetermined threshold, the alarm is activated. This mechanism effectively allows for the rapid detection of smoke, which is crucial in fire safety applications.

The other options involve different concepts that do not pertain to the specific functioning of light scattering detectors. For example, temperature changes and increases in air pressure can indicate fire presence, but they do not directly trigger the alarm in a light scattering detector. Similarly, absorption of light by smoke particles is a different mechanism that does not account for the principle by which these particular detectors operate.