Coin-sized nuclear 3V battery with 50-year lifespan enters mass production
(www.techspot.com)
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Don't smoke detectors work by detecting radiation?
No, not by detecting RADIATION but by detecting smoke or anything that interferes with the radiation tripwire. Imagine a photoelectric cell that is constantly on (except that this is a field generated by a small radioactive element) and a person walks through the light beam and sets off the alarm. Same with smoke in this case, it interferes with the field emitted by the Americium contained in the smoke detector. So it's not really detecting radiation, but for the lack of it. That's the best analogy I can make.
So, they DO detect radiation ---- and look for a drop.
No, the radiation ionizes the air inside the device and creates an air flow allowing the air to constantly flow through the detector to be sampled. The smoke is detected by other means such as breaking a photoelectric beam.
AKA radiation ---- smoke stops Alpha radiation
Smoke detectors work by detecting Alpha radiation changes.
Gamma rays don't give a shit and go through everything, but Alpha rays get stopped easily.
...thus it detects the absence of radiation...
To detect the absence of radiation you have to detect radiation.
No one said where the radiation came from.
It works by detecting radiation.
Photocells work by detecting light --- sun or flashlight or infrared LED, doesn't give a shit
I have to say, I do not know that answer. Damn it cyberrigger, now I have to find out how smoke detectors work before I’ll be able to sleep.
They come with an Alpha radiation source (easily blocked by smoke).
This radiation passed through air.
A detector looks for a drop in radiation, because of smoke.
Oh, so it’s a question you already knew the answer too you sly dog, I see how you play the game.
Don't you remember the "safer" radioactive watch dials that used alpha particle radiation to glow? ----- instead of the old, dangerous radium dials (beta and gamma radiation)?
Alpha penetrates the least
Beta penetrates more things
Gamma ----- this shit goes through everything
Alpha stops at your skin
That's the ionisation type. There are others, such as optical (beam of light broken by smoke) and heat detectors which use a thermocouple detecting either a fixed temperature or a sufficiently rapid rate of rise. There is another, aspirating, but that is not used in homes, it relies on sampling air and creating a rapid pressure drop at intervals. If there are hygroscopic nuclei in the air (smoke or the precursors) a "cloud" will form and that is optically sensed, they are used in warehouses typically, because they are good for early warning of fire, before it even starts often (strike a match and it goes off even if you blow out the match immediately).
No, they don't. The radioactive element ionizes the air inside the device and causes the air to flow. The air flow causes the smoke particles to be drawn in to be continuously sampled and detected. This is the same way that the ionizing foil detectors are used to indicate radioactivity. The ionized air flow deflects a small strip of foil creating a visual indication that radioactivity is present.