The two basic types of smoke detectors are photoelectric and which?

The two basic types of smoke detectors are photoelectric and which?

• A. Rate of Rise
• B. Fixed Temperature
• C. Ionization
• D. Laser Beam

Answer: (C)

Two basic smoke detection methods use different sensing principles. Photoelectric detectors rely on light scattering: a beam is produced inside a chamber, and when smoke enters, the particles scatter the light toward a sensor, triggering the alarm. Ionization detectors use a small amount of radioactive material to ionize the air between two plates, creating a steady current; when smoke enters, it disrupts the current and the alarm sounds. The other options aren’t the standard smoke-detection types—heat detectors use rate of rise or fixed temperature, and laser beam detectors are a specialized design, not the fundamental pair. So Ionization is the other basic type alongside photoelectric.

Two basic smoke detection methods use different sensing principles. Photoelectric detectors rely on light scattering: a beam is produced inside a chamber, and when smoke enters, the particles scatter the light toward a sensor, triggering the alarm. Ionization detectors use a small amount of radioactive material to ionize the air between two plates, creating a steady current; when smoke enters, it disrupts the current and the alarm sounds. The other options aren’t the standard smoke-detection types—heat detectors use rate of rise or fixed temperature, and laser beam detectors are a specialized design, not the fundamental pair. So Ionization is the other basic type alongside photoelectric.