So it wa a about 10pm and my whole family was settling into bed. Suddenly, our smoke detectors went off! It just beeped once and turned off! We all ran downstairs and was about to leave the house thinking there was a fire, but there wasnt one! My dad checked from the attic down to the basement. Why did this happen? Could it be the batteries? Usually when it's low battery ours say BEEP BEPP LOW BATTERY. I'm so paranoid and can't sleep :(
i could seize my 134 pound projection television, my computing gadget and visual show unit, a pair of window unit AC's, my stereo, and something of my digital crap. i could seize all of this interior a similar time it may take you to seize your 3 issues. i could seize a gaggle of garments too.
Yeah, it's more cliche'd drivel from some kind of logorrheic robot called Lang Leav, who strews crap all over the internet.
There are two main types of smoke detector: photoelectric and ionisation. The photoelectric sort relies on a beam of light being deflected or interrupted by smoke particles. However, the one we're interested in is the ionisation type. In this type, a small amount of americium is held within the chamber, between two metal plates that are about a centimetre apart. The space between these plates is a gap in the alarm circuit in the alarm. Under normal conditions, the alpha radiation from the americium knocks out electrons from the molecules of oxygen and nitrogen that make up most of our air as they flow through the detector, turning them in to ions (charged particles), which conduct electricity. Therefore, the current in the alarm circuit can flow between the plates, and the circuit is complete. An integrated circuit can detect this normal flow, and keeps the alarm silent. If smoke flows in to the chamber, the smoke particles absorb a lot of the ionising radiation from the americium, so it can no longer ionise the air, and therefore, no current flows between the plates. The integrated circuit detects this drop in current and sounds the alarm. Americium has a few properties that make it a good choice: 1) There's lots of it available; it's a byproduct of some types of nuclear reaction. 2) It gives out mainly alpha radiation: this is strongly ionising, but can be stopped by a few centimetres of air. This means the americium can do its job in the chamber, but no radiation will escape outside where it could be a health hazard. Americium does give off a small proportion of gamma rays, but these are minimal, and far below your average dose from background radiation. 3) It has a half-life of 432 years, meaning it remains radioactive (and therefore able to do its job) for well past the useful life of the detector. Hope this helps :)
