Smokedetectors are devices that detect smoke, in case of fire.
Smoke detectors arelocated in almost every house and are there to help you know if there is afire. Francis Upton was the first to introduce the automatic electric firealarm. In 1902, George Andrew Darby patented the first electric heat detector.
Another while later, in the late 1930’s Walter Jaeger thought he invented asensor for poison gas. His invention failed as it did not detect small amountsof gas. However, he accidently discovered that his sensor detected smoke. Outfrustration that his sensor for poison gas did not work he started to smoke acigarette and he saw that this moved the meter on his sensor. So, from a failedinvention to the lifesaving gadget in almost everyone’s house.Smokedetectors, give out Alpha radiation. Alpha particles have 2 protons and 2neutrons. This tells us that they have a charge of +2, and a mass of 4.
Alphaparticles are relatively slow and heavy. Alpha emitters must be used for smokedetectors since alpha particles ionize air the most, are mostly likely to beabsorbed by cells and are least penetrating. Gamma rays and beta particleseasily pass through air without causing ionization, Beta particles are absorbedby a thin sheet of Aluminium and Gamma is absorbed by either concrete or thicklead.Theradiation given out from a smoke detectors is so small that it is almost zero.This radiation is also less than the background radiation. Background radiationis the radiation that is always present everywhere. The background radiation isso small that it does not harm humans and can hardly be detected.
So, the smallamount of radiation used by a smoke detector is not harmful to humans. However,if the Alpha radiation is inside the body, the Alpha radiation is most harmfulas they are absorbed by the organs. Beta and Gamma radiation on the other handis more dangerous outside the body as the skin is not able to stop theseradiations and they would penetrate through. So, the Americium-241 used insmoke detectors is not dangerous at all unless it is inside the body.Americium-241 is aradioactive substance which emits Alpha radiation. The first successful attempt to createAmericium-241 was in 1945, to create Americium-241 they used Plutonium-239, aradioactive isotope of Plutonium and by bombarding this with neutrons.
Theresulting substance was Plutonium-240, then they bombard the plutonium-240 withneutrons which produces Plutonium-241. The decay of the Plutonium-241 resultedin the Americium-241.The half-life for Americium-241 is 432.2 years. This meansit take 432.2 years for the radioactivity of the Americium-241 to fall to halfits original value. The size of the Americium-241 in a smoke detectors is verysmall as well which causes it to emit less radioactivity. In theimage below you can see a smoke detector.
The smoke detector has differentparts with different roles. The alarm’s battery sends a voltage to the plates,charging one positive and the other negative. The radiation source, a smallamount of Americium-241, decays and emits alpha particles at a reliable, constant rate. As the particlestravel through the chamber, they ionize the oxygen and nitrogen atoms in theair that passes through the chamber.The newlyfree electrons, which have a negative charge, are attracted to the positivelycharged plate, and the now-positively charged atoms are attracted to thenegative plate. This maintains a small but constant current between the twoplates. If there was a fire and the smoke would go into the chamber, it would disruptsthis current between the two plates, this then would trigger the alarm.The battery of a smokealarm sends out a voltage to plates,by doing this it charges one positive and onenegative.
A very small amount of Americium-241, which is the radiation sourceof a smoke detector. This small amount of Americium-241decays and as it decays,at a constant rate it emits alpha particles. There are several advantages and disadvantagesof smoke detectors. Below are some advantages. The most important advantage of smoke detectors isof course the fact that is saves lives. They also help inform emergencyservices like the fire brigade to react quicker, which helps them to get to thefire quicker and prevent it from spreading. Besides this, smoke detectors alsohave an economical factor which is that is saves money and property.
In case ofa fire a smoke detector can warn someone of a fire and someone might than beable to save the property or possible money in the house. With a smoke detector, a personis able to quickly put out the fire so a lot of the property does not getdamaged. Another advantage is that the Americium-241 is very sensitive. Because these smoke detectors are so sensitivethey also respond very quickly to small amounts of smoke.
This also helpsinsurance companies as it would cost them less money because people are warnedvery soon and are able to prevent the fire from spreading or putting the fireout. It is very easy to install a smoke detector and they are relatively cheapas well. Americium-241 has a half-life of 442 which isnot too long or too short. It is just right. If it had a longer half-life thenit wouldn’t have to be replaced very often but it would stay dangerous for along time.
If it had a short half-life then it would fall to safe level quicklybut it would have to be replaced very often. The Americium-241 is just right,not too short or too long, right in between.On theother hand, there are disadvantages, the biggest disadvantage is that itcontains a small amount of radioactive material. This radioactive material isnot really hazardous unless they burn, which would release the Americium-241 inan inhalation hazard. Also, which could be seen as an advantage as well is thatthey are very sensitive which could cause them to go off when there isn’t evena fire. There could be a lot of steam from for example cooking and it might gooff, this could cause noise complaints and can be very irritating or even makeyou think there is a fire when there’s actually no fire.Anotherdisadvantage is that there is such a huge amount of smoke detectors and theyall give out radiation. They will be radioactive for 100’s of years, thisradioactivity will keep increasing in the environment.
The disposal of thesesmoke detectors is harmful as well as they still emit radioactivity which overtime is not good for the environment and after a long time all of this couldhave an effect on humans.To sum upeverything that was mentioned above, the smoke detector was a good invention.It saves lives and helps the people in the building or home and informs theemergency services quicker. The Americium-241 used in smoke detectors are notharmful to humans as the radioactivity emitted by the Americium-241 is almostzero.