Most fires occur at night when people are sleeping.
A smoke detector can alert you when there is a fire, in time to save your life. Smoke detectors work by sensing rising smoke from a fire and sounding an alarm. Photoelectric uses a photoelectric bulb that sends forth a beam of light. When smoke enters, light from the beam is reflected from smoke particles into a photocell and the alarm is triggered. Ionization Chamber contains a small, safe radiation chamber source that produces electrically charged air molecules called ions.