Smoke detectors which use a light source and a photosensitive sensor can be:

Smoke detectors which use a light source and a photosensitive sensor can be:

• A. Ionization smoke detectors
• B. Photoelectric light scattering detectors
• C. Heat detectors
• D. Combination detectors

Answer: (B)

This is about optical smoke detectors. They work by shining a light inside a chamber and having a photosensitive sensor detect light reaching it. In clean air, the beam doesn’t hit the sensor, but when smoke enters, the particles scatter the light toward the sensor and trigger the alarm. This describes a photoelectric detector of the light-scattering type. Ionization detectors rely on ion currents and don’t use a light beam. Heat detectors respond to temperature changes, not smoke. Combination detectors may use multiple technologies, but the description given fits the photoelectric light-scattering design best.

This is about optical smoke detectors. They work by shining a light inside a chamber and having a photosensitive sensor detect light reaching it. In clean air, the beam doesn’t hit the sensor, but when smoke enters, the particles scatter the light toward the sensor and trigger the alarm. This describes a photoelectric detector of the light-scattering type. Ionization detectors rely on ion currents and don’t use a light beam. Heat detectors respond to temperature changes, not smoke. Combination detectors may use multiple technologies, but the description given fits the photoelectric light-scattering design best.