What is the difference between Ionization or Optical smoke detectors?
The other answers all have some elements of truth. Ionization-type smoke detectors utilize a radioactive source to establish a current between two electrodes. Smoke particles (and some other things) interfere with ion mobility, and reduce the current. At some level, the detector goes into alarm. Photoelectric-type detectors utilize a light source and a photosensitive element, placed so that it doesn’t see the light. Smoke particles scatter the light so the photosensitive element sees light from the particles. Just as you can see dust particles in sunlight. Photoelectric-type detectors are best for almost all conditions, and especially the home. Some knowledgeable experts think ionization-type smoke detectors should be outlawed for home use, because of the differences in detecting ability for home fires.
