Which of the following is not a type of smoke detector?

Which of the following is not a type of smoke detector?

• A. Ionization
• B. Photoelectric
• C. Heat detector
• D. Light obscuration

Answer: (C)

Smoke detectors alert based on particles or light interactions in the air, not on heat. The main types of smoke detectors are ionization, which uses a small radioactive source to create ionized air and triggers when smoke disrupts that current, and photoelectric (optical), which detects smoke by how it affects light—either by scattering light to a sensor or by obscuring a light beam. Light obscuration is a recognized method within optical detection, where smoke blocks a light path and the sensor responds. A heat detector, by contrast, responds to heat—either a fixed high temperature or a rapid temperature rise—and does not detect smoke particles. So the one not a smoke detector is the heat detector.

Smoke detectors alert based on particles or light interactions in the air, not on heat. The main types of smoke detectors are ionization, which uses a small radioactive source to create ionized air and triggers when smoke disrupts that current, and photoelectric (optical), which detects smoke by how it affects light—either by scattering light to a sensor or by obscuring a light beam. Light obscuration is a recognized method within optical detection, where smoke blocks a light path and the sensor responds. A heat detector, by contrast, responds to heat—either a fixed high temperature or a rapid temperature rise—and does not detect smoke particles. So the one not a smoke detector is the heat detector.