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Uses of radioactivity


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Background radiation is all around us and is mostly unavoidable. Most background radiation comes from natural sources, while most artificial radiation comes from medical examinations, such as x-ray photographs. Radiation has many uses. We measure the radioactivity of a source using half-lives.

Background radiation

You should know some of the sources of natural background radiation.


Radiation is all around us. It comes from radioactive substances including the ground, the air, building materials and food. Radiation is also found in the cosmic rays from space.


SourceType of radiation

Cosmic radiation

Cosmic rays

Radiation that reaches the Earth from outer space

A cow


All animals emit natural levels of radiation

Some rocks


Some rocks give off radioactive radon gas

A plant

Soil and plants

Radioactive materials from rocks in the ground are absorbed by the soil and hence passed on to plants

Some rocks contain radioactive substances that produce a radioactive gas called radon. The left-hand pie chart shows the average contribution of these different sources to our natural background radiation.

50% radon gas from the ground, 12%  buildings and the ground, 12% food and drink, 12% cosmic rays, 14% artificial sources - mainly cosmic rays, small amount of nuclear power and weapons test

Average contribution of different sources to natural background radiation


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