What are the two main types of smoke detectors commonly used in buildings?

The two main types of smoke detectors commonly used in buildings are ionization and photoelectric smoke detectors. Ionization smoke detectors are designed to detect fast-burning fires that produce little visible smoke, using a small amount of radioactive material to ionize the air in a sensing chamber. When smoke enters the chamber, it disrupts the ionization process, triggering the alarm.

Photoelectric smoke detectors, on the other hand, utilize a light beam and a light sensor. In the event of smoke from a slow-burning fire, the smoke particles scatter the light, which is detected by the sensor, activating the alarm. This type is particularly effective for detecting smoldering fires, which produce more visible smoke.

These two technologies complement each other, making them widely popular in residential and commercial settings to ensure comprehensive fire detection capabilities. The other options, while related to fire detection and safety, do not represent the main types of smoke detectors typically found in buildings.