Which type of smoke detector detects smoke by shining a beam of light through the chamber and sensing scattered light with a photocell?

Which type of smoke detector detects smoke by shining a beam of light through the chamber and sensing scattered light with a photocell?

• A. Ionization Smoke Detector
• B. Photoelectric Smoke Detector
• C. Smoke Detector
• D. Heat Detector

Answer: (B)

Detecting smoke by shining a beam of light and sensing scattered light with a photocell is how optical (photoelectric) smoke detectors work. In this type, a light source sits inside a chamber; under normal conditions the light path doesn’t reach the sensor. When smoke particles enter, they scatter the light, and some of that scattered light is picked up by the photocell, triggering the alarm. Ionization detectors, by contrast, use a radioactive source to ionize air and respond more quickly to flaming fires, not to scattered light. Heat detectors respond to temperature changes rather than smoke. So the described method is the optical/photoelectric detector.

Detecting smoke by shining a beam of light and sensing scattered light with a photocell is how optical (photoelectric) smoke detectors work. In this type, a light source sits inside a chamber; under normal conditions the light path doesn’t reach the sensor. When smoke particles enter, they scatter the light, and some of that scattered light is picked up by the photocell, triggering the alarm. Ionization detectors, by contrast, use a radioactive source to ionize air and respond more quickly to flaming fires, not to scattered light. Heat detectors respond to temperature changes rather than smoke. So the described method is the optical/photoelectric detector.