Smoke every house and are there to help you

Smoke
detectors are devices that detect smoke, in case of fire. Smoke detectors are
located in almost every house and are there to help you know if there is a
fire. Francis Upton was the first to introduce the automatic electric fire
alarm. In 1902, George Andrew Darby patented the first electric heat detector.
Another while later, in the late 1930’s Walter Jaeger thought he invented a
sensor for poison gas. His invention failed as it did not detect small amounts
of gas. However, he accidently discovered that his sensor detected smoke. Out
frustration that his sensor for poison gas did not work he started to smoke a
cigarette and he saw that this moved the meter on his sensor. So, from a failed
invention to the lifesaving gadget in almost everyone’s house.

Smoke
detectors, give out Alpha radiation. Alpha particles have 2 protons and 2
neutrons. This tells us that they have a charge of +2, and a mass of 4. Alpha
particles are relatively slow and heavy. Alpha emitters must be used for smoke
detectors since alpha particles ionize air the most, are mostly likely to be
absorbed by cells and are least penetrating. Gamma rays and beta particles
easily pass through air without causing ionization, Beta particles are absorbed
by a thin sheet of Aluminium and Gamma is absorbed by either concrete or thick
lead.

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The
radiation given out from a smoke detectors is so small that it is almost zero.
This radiation is also less than the background radiation. Background radiation
is the radiation that is always present everywhere. The background radiation is
so small that it does not harm humans and can hardly be detected. So, the small
amount 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 harmful
as they are absorbed by the organs. Beta and Gamma radiation on the other hand
is more dangerous outside the body as the skin is not able to stop these
radiations and they would penetrate through. So, the Americium-241 used in
smoke detectors is not dangerous at all unless it is inside the body.

Americium-241 is a
radioactive substance which emits Alpha radiation. The first successful attempt to create
Americium-241 was in 1945, to create Americium-241 they used Plutonium-239, a
radioactive isotope of Plutonium and by bombarding this with neutrons. The
resulting substance was Plutonium-240, then they bombard the plutonium-240 with
neutrons which produces Plutonium-241. The decay of the Plutonium-241 resulted
in the Americium-241.The half-life for Americium-241 is 432.2 years. This means
it take 432.2 years for the radioactivity of the Americium-241 to fall to half
its original value. The size of the Americium-241 in a smoke detectors is very
small as well which causes it to emit less radioactivity.    In the
image below you can see a smoke detector. The smoke detector has different
parts with different roles. The alarm’s battery sends a voltage to the plates,
charging one positive and the other negative. The radiation source, a small
amount of Americium-241, decays and emits alpha particles at a reliable, constant rate. As the particles
travel through the chamber, they ionize the oxygen and nitrogen atoms in the
air that passes through the chamber.

The newly
free electrons, which have a negative charge, are attracted to the positively
charged plate, and the now-positively charged atoms are attracted to the
negative plate. This maintains a small but constant current between the two
plates. If there was a fire and the smoke would go into the chamber, it would disrupts
this current between the two plates, this then would trigger the alarm.

The battery of a smoke
alarm sends out a voltage to plates,
by doing this it charges one positive and one
negative. A very small amount of Americium-241, which is the radiation source
of 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 disadvantages
of smoke detectors. Below are some advantages.

The most important advantage of smoke detectors is
of course the fact that is saves lives. They also help inform emergency
services like the fire brigade to react quicker, which helps them to get to the
fire quicker and prevent it from spreading. Besides this, smoke detectors also
have an economical factor which is that is saves money and property. In case of
a fire a smoke detector can warn someone of a fire and someone might than be
able to save the property or possible money in the house. With a smoke detector, a person
is able to quickly put out the fire so a lot of the property does not get
damaged. Another advantage is that the Americium-241 is very sensitive. Because these smoke detectors are so sensitive
they also respond very quickly to small amounts of smoke. This also helps
insurance companies as it would cost them less money because people are warned
very soon and are able to prevent the fire from spreading or putting the fire
out. It is very easy to install a smoke detector and they are relatively cheap
as well.    

Americium-241 has a half-life of 442 which is
not too long or too short. It is just right. If it had a longer half-life then
it wouldn’t have to be replaced very often but it would stay dangerous for a
long time. If it had a short half-life then it would fall to safe level quickly
but it would have to be replaced very often. The Americium-241 is just right,
not too short or too long, right in between.On the
other hand, there are disadvantages, the biggest disadvantage is that it
contains a small amount of radioactive material. This radioactive material is
not really hazardous unless they burn, which would release the Americium-241 in
an inhalation hazard. Also, which could be seen as an advantage as well is that
they are very sensitive which could cause them to go off when there isn’t even
a fire. There could be a lot of steam from for example cooking and it might go
off, this could cause noise complaints and can be very irritating or even make
you think there is a fire when there’s actually no fire.Another
disadvantage is that there is such a huge amount of smoke detectors and they
all give out radiation. They will be radioactive for 100’s of years, this
radioactivity will keep increasing in the environment. The disposal of these
smoke detectors is harmful as well as they still emit radioactivity which over
time is not good for the environment and after a long time all of this could
have an effect on humans.

To sum up
everything 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 the
emergency services quicker. The Americium-241 used in smoke detectors are not
harmful to humans as the radioactivity emitted by the Americium-241 is almost
zero.