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radioactive smoke alarms?

why do some smoke alarms contain americium and how is it used?

Public Comments

  1. It uses the radiation as a smoke detector.
  2. Americium-241 is an alpha particle emitter, (it also emits gamma rays) and a smoke detector takes advantage of this ionizing radiation. When there is no smoke, a current is able to pass through a space in the detector; if smoke is present it takes up the alpha radiation and halts the current. This trips the smoke detector. You can find more information at the following sites: http://dwb.unl.edu/Teacher/NSF/C03/C03Links/www.uic.com.au/nip35.htm http://en.wikipedia.org/wiki/Smoke_detector
  3. A membrane made of Americium will raise and lower in resistance with the presence of radiation emitted by smoke particles. The difference in resistance is picked up by an op-amp circuit, and the alarm will sound.