Smoke alarms

[c/w]

How do smoke alarms work?
What do you think of smoke are they good or bad? (state why)

[Mattk]

They work by measuring impurities in the air and of course they are a good thing !

[Panic Button]

A radio active source and a sensor detecting radiation given off. If smoke comes between the two it reduces the radiation detected.

It then starts bleeping and you start flapping your tea towel to disperse the smoke, before scraping the toast and buttering it.

[spudqueen]

What do I think of smoke or what do I think of smoke alarms? If you are asking what do I think of smoke alarms then I think they are a good thing. If my friend had had one fitted he may well not have died in a fire in his house, going on for seven years ago now.

[nightmare]

Panic Button
not quite correct.
A radioactive source (Americium 241) which is an alpha emitter ionises the air between two plates, between which is a voltage. This produces a small electric current.
Any smoke particles entering the gap between the plates attract some of the ions and consequently, the current is decreased.
This is sensed by the detector circuitry, setting off the alarm.
The radiation per se is unaffected.

[LeMarchand]

Sounds like an essay question to me...

[Panic Button]

I stand corrected.