How does a Photoelectric Smoke Detector detect smoke?

How does a Photoelectric Smoke Detector detect smoke?

• A. Uses a small light source, either an incandescent bulb or a light emitting diode to detect smoke. It is done by shining a light through the chamber and smoke particles reflect it.
• B. Measures ionization of air with a radioactive source.
• C. Detects heat produced by smoke.
• D. Detects smoke by color change on sensor.

Answer: (A)

Photoelectric smoke detectors sense smoke by how particles scatter light. In this type, a small light source, usually an LED (or sometimes a tiny incandescent), shines light into a sensing chamber. When smoke enters, the particles scatter the light so that some of it reaches a photosensitive detector, which then triggers the alarm. This method is particularly effective for detecting smoldering fires that produce a lot of smoke before flames appear. The other options describe ionization detectors (which use a radioactive source to ionize air), heat detectors (which respond to heat), or a color-change sensor—none of which describe how a photoelectric detector actually works.

Photoelectric smoke detectors sense smoke by how particles scatter light. In this type, a small light source, usually an LED (or sometimes a tiny incandescent), shines light into a sensing chamber. When smoke enters, the particles scatter the light so that some of it reaches a photosensitive detector, which then triggers the alarm. This method is particularly effective for detecting smoldering fires that produce a lot of smoke before flames appear. The other options describe ionization detectors (which use a radioactive source to ionize air), heat detectors (which respond to heat), or a color-change sensor—none of which describe how a photoelectric detector actually works.