Definition - What does Smoke Detector mean?
A smoke detector is a sensor that detects smoke as a primary indication of fire. It provides a signal to a fire alarm system in a large building, or produces an audible and visual signal locally in a room or a home. Smoke detectors are usually housed in a small, round shaped plastic case, and placed at the roof where there are risks of fire or fire hazards.
Safeopedia explains Smoke Detector
There are two main types of smoke detectors: photoelectric and ionization. When smoke enters the detector chamber, a photoelectric type detects sudden scattering of light, whereas an ionization type detects the change of electrical current flow that triggers the signal - indicating the presence of smoke.
Smoke detectors have an average life of about 10 years. Detectors need to be tested periodically and the batteries changed when required. Ionization types contain radioactive material called Americium. The amount of radiation from Americium, generally, is not harmful, but intake through the mouth or inhalation by children may cause health issues. When used at home, some detectors use both technologies in combination with heat detectors to be more accurate.