Ionization smoke detectors use americium
Why is it safe to use a source of alpha radiation in smoke alarms in a house?
An alpha source is used because alpha radiation does not penetrate very far . It is absorbed by a few cm of air. This means that as long as the detector is high up on a wall, or the ceiling, it is safe for humans to be in the same room.
Why does a smoke alarm only work with Alpha?
Alpha radiation ionises the air and this allows a small current to flow between two electrodes. Alpha is weakly penetrating so smoke stops it , the current drops and the alarm goes off. The isotope should be an alpha emitter with a long half-life. This means the smoke alarm will not need to be changed daily.
Why is alpha radiation used in smoke detectors and not beta or gamma?
The main reason that alpha particles are used is that they are strongly ionizing , because they are helium nuclei without any orbiting electrons; they will rip electrons off of any particles that they encounter, whereas gamma rays and beta particles will not.
Why is there a radioactive source in a smoke detector?
Why is there a radioactive source in a smoke detector? it makes the smoke particles radioactive. it ionizes the air . it powers the alarm when the battery wears out.
What is the most suitable radioisotope for a smoke detector?
Smoke detectors are very safe
Most units sold today use one microcurie or less of americium-241 . A 2001 NRC study found people with two of these units in their homes receive less than 0.002 millirems of radiation dose each year.
What happens if you touch americium?
Alpha particles are relatively high energy particles, but travel only extremely short distances and do not penetrate the skin. However, if americium is taken into the body and enters body tissues, alpha particles may produce damage to nearby cells .
Why are radioisotopes used in exit signs and smoke detectors?
EXIT signs: Some EXIT signs contain the radioactive gas called tritium, allowing them to glow in the dark without electricity or batteries. The tritium used in EXIT signs gives off low-level beta radiation, causing a light-emitting compound to glow .
How is alpha decay used in everyday life give at least two examples?
Alpha radiation is used as an energy source to power heart pacemakers . Plutonium-238 is used as the fuel source for such batteries; with a half-life of 88 years, this source of power provides a long lifespan for pacemakers.
Are alpha particles used in smoke alarms?
Ionization smoke detectors use americium as a source of alpha particles. Alpha particles from the americium source ionize air molecules. This makes some particles positively charged and some negatively charged.
Why would a smoke alarm not work with a radiation source that emits beta or gamma radiation?
The radioactive source emits alpha particles. The alpha particles ionise the air inside the sensor which causes a small electric current. ... The change in current sets the alarm off. (i) The smoke detector would not work if a radioactive source that emitted only gamma rays was used .
Which type of radiation should be used to check the thickness of the foil?
Thickness monitoring
Radiation is absorbed as it passes through materials. This allows it to be used to gauge the thickness of a material by measuring the amount of radiation that passes through. This is commonly used with beta minus emitters in industry, for paper milling and the production of aluminium foil.
What is the difference between irradiation and contamination?
The key difference between radioactive contamination and irradiation is that radioactive contamination occurs when there is direct contact with radioactive substances , whereas irradiation occurs when there is indirect exposure to radioactive substances.
Do smoke detectors still used americium?
No. Fires kill people but smoke detectors don’t even irradiate them . ... Ionization chamber smoke detectors contain a small amount of americium-241, a radioactive material. Smoke particles disrupt the low, steady electrical current produced by radioactive particles and trigger the detector’s alarm.
Is it OK to throw away smoke detectors?
Ionisation smoke alarms contain a very small amount of a radioactive material, Americium-241. The general recommendation, even from EPAs, is that smoke alarms be disposed of in general household waste . ... The EPA in New South Wales does also mention taking smoke detectors to community recycling centres.
How much radioactive material is in a smoke detector?
1, a typical modern detector contains about 1.0 microcurie of the radioactive element americium, which is equivalent to 37 kilobecquerel (37,000 decays per second), or 0.33 micrograms of americium oxide (AmO 2 ).
