A radioactive source “decays,” or sheds particles and photons from unstable atoms. The particles interact with neutral air molecules flowing through the chamber. The particles remove electrons from air molecules, creating positive ions .
Why do smoke detectors emit alpha particles?
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. ... The smoke alarm triggers when smoke breaks the constant flow of ions .
Why are radioisotopes used in smoke detectors?
One of the most common uses of radioisotopes today is in household smoke detectors. ... These ‘ionisation chamber’ smoke detectors are the most popular because they are inexpensive and are more sensitive to flaming fire conditions with little smoke than the other type . They contain americium.
What do the alpha particles do to the oxygen and nitrogen atoms in the chamber of a smoke detector?
Radioactive isotopes which emit alpha particles can be used in smoke detectors. The alpha particles emitted from the Americium-241 collide with the oxygen and nitrogen molecules in the air causing them to ionise . ... To ionise means to knock off electron/electrons from an atom.
What are alpha particles used for?
Alpha particles are charged particles, which are emitted from naturally occurring materials (such as uranium, thorium, and radium) and man-made elements (such as plutonium and americium). These alpha emitters are primarily used (in very small amounts) in items such as smoke detectors .
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 .
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.
How do isotopes work in smoke detectors?
An unstable isotope undergoes nuclear decay (radioactive decay) by emitting radiation. Normally, charged particles in the air allow a current to flow through the detector. Smoke particles in a fire prevent the current flowing causing an alarm to sound.
Is alpha decay used in smoke detectors?
An isotope of americium which emits alpha particles is used in smoke alarms. ... 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.
How is radioactive decay used in smoke detectors?
Ionization chamber smoke detectors rely on radiation to “ionize” the air inside the chamber . A radioactive source “decays,” or sheds particles and photons from unstable atoms. ... Two electrodes, or charged plates, attract the ions, creating a small but steady current.
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.
Why are beta particles not used in smoke detectors?
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.
Do smoke detectors have uranium?
The isotope of americium used in smoke detectors is americium-241, which decays by α emission to neptunium-237 with a half-life of 432.2 years. ... Plutonium-239 is itself the primary fissile isotope of plutonium (used in nuclear weapons), and is in turn made from uranium .
Are alpha particles harmful to humans?
Alpha particles lack the energy to penetrate even the outer layer of skin, so exposure to the outside of the body is not a major concern. Inside the body, however, they can be very harmful . ... The way these large, heavy particles cause damage makes them more dangerous than other types of radiation.
Which is the correct symbol for an alpha particle?
| Alpha decay | Composition 2 protons, 2 neutrons | Statistics Bosonic | Family l | Symbol α , α 2 + , He 2 + |
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Is alpha particle positive or negative?
A positively charged particle ejected spontaneously from the nuclei of some radioactive elements. It is identical to a helium nucleus that has a mass number of 4 and an electrostatic charge of +2. It has low penetrating power and a short range (a few centimeters in air).
