Smoke Detector Simulation
Smoke detectors are important safety devices that are in many modern homes. Two types of smoke detectors exist. One type uses a photoelectric sensor to detect changes in light caused by smoke, and the other uses radioisotopes - usually americium-241. (American spelling: americum) The photoelectric type is more expensive and is less effective, whereas the other type is much cheaper and more sensitive to a wider range of fire conditions. These radioisotope-based detectors are the most common.
Inside a radioisotope-based smoke detector, the americium-241 is placed inside an air chamber. The ionising alpha radiation emitted collides with air moleculrs in the air chamber, ionising them (making the air particles charged). The ionised air molecules are then able to conduct an electrical current between two electrodes on either side of the air chamber.
When smoke enters the air chamber, the ionised air molecules attract the smoke particles, causing a decrease in the current conducted. (The ionised air molecules are now "carrying" extra smoke particles, decreasing the flow of current.) This current decrease is then detected by electrical circuitry, activating an alarm.