Atomic Structure - 4.3.1 Background Radiation (GCSE Physics AQA)

Background Radiation

Background Radiation Sources

• Background radiation is all around us. In the air around us, there is always a low level of background radiation. This radiation will comes from various sources.
• Background radiation can come from natural sources. Rocks are a natural source of background radiation, whilst cosmic rays can bring background radiation from space. Food and drink can even be natural sources of background radiation. The unstable isotopes in these sources will lead to the background radiation.
• Background radiation can come from man-made sources. Sometimes, the background radiation can come from a man-made source. These sources tend to be from nuclear weapons testing and nuclear accidents. Although these are very dangerous sources of unstable isotopes, they only make up a small amount of all background radiation.

Factors Affecting Radiation Dose

• We all experience background radiation. On Earth, we all experience a low level of background radiation. This comes from the sources that we previously mentioned.
• Occupation can affect exposure. Certain types of jobs can affect exposure to radiation. For example, pilots and air hostesses are exposed to more cosmic radiation. Similarly, radiology technicians work with X rays, exposing them to more radiation.
• Location can affect exposure. Certain locations will have a higher level of background radiation compared to other locations. This is due to rocks having different amounts of unstable nuclei, leading to varying amounts of background radiation.

Measuring Radiation

• We can measure background radiation. Using a Geiger-Muller tube, we can measure the level of background radiation in the air. The Geiger-Muller tube should be placed away from any known sources of radiation, so that we can get an accurate measurement for background radiation.
• The unit of radiation is the sievert. Sieverts are the units of the radiation. The symbol for sievert is Sv. Like most other units, sieverts can come in different factors, such as millisieverts (mSv).
• Millisieverts make up sieverts. 1000 millisieverts make up one sievert. Since background radiation is at such a low level, you will commonly see the unit mSV rather than the unit Sv.