Answer the question give details.
it detects carbon monoxide in the air.
The smoke stops a circuit which starts the alarm. See my pedia link. Also try HowStuffWorks. I'd look but it's a very slow loading site.
Everything, just about! Wearing dresses, sandals and heels, motorcycle riding, tan skin, warm weather, the sun, boating with my family, cookouts, festivals in my state, not being cold, long walks, cold beer, Derby (though technically it's still Spring when Derby goes on, but you catch my drift, Fairs and amusement parks, cute clothes, riding in my Mustang with the windows down, the list goes on and on!! :D
A smoke detector or smoke alarm is a device that detects smoke and issues an alarm to alert nearby people that there is a potential fire. Technically, they could also be described as an active fire protection device that is subject to stringent bounding. A household smoke detector will typically be mounted in a disk shaped plastic enclosure about 150mm in diameter and 25mm thick, but the shape can vary by manufacturer. Because smoke rises, most detectors are mounted on the ceiling or on a wall near the ceiling. To avoid the nusance of false alarms, most smoke detectors are mounted away from kitchens. To increase the chances of waking sleeping occupants, most homes have at least one smoke detector near any bedrooms; ideally in a hallway as well as in the bedroom itself. Smoke detectors are usually powered by one or more batteries but some can be connected directly to household wiring. Often the smoke detectors that are directly connected to household wiring also have a battery as a power supply backup in case the household wiring goes out. It is usually necessary to replace the batteries once a year to ensure appropriate protection. Most smoke detectors work either by optical detection or by ionization, but some of them use both detection methods to increase sensitivity to smoke. Smoke detectors may operate alone, be interconnected to cause all detectors in an area to sound an alarm if one is triggered, or be integrated into a fire alarm or security system. Smoke detectors with flashing lights are available for the deaf or hearing impaired. A smoke detector cannot detect carbon monoxide to prevent carbon monoxide poisoning unless it has an integrated carbon monoxide detector.
