4.2.3

Detection

Test yourself

Detecting Radioactivity

There are three primary ways of detecting radioactivity.

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Geiger counter (Geiger-Muller tube)

  • Ionising radiation enters a tube full of low-pressure gases.
  • It ionises the atoms in the gas, knocking electrons out of the atoms.
  • The gas can now conduct electricity and completes an electric circuit. Current flows between electrodes.
  • The current produces a clicking noise.
  • The count-rate is the number of decays recorded each second.
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Photographic film

  • Ionising radiation has the same effect on photographic film as light.
  • A bright spot appears wherever the ionising radiation hits the film.
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Cloud chamber

  • A cloud chamber is a container full of air containing alcohol vapour.
  • Ionising radiation enters the air and leaves a trail of ionised air molecules.
  • The alcohol vapour condenses on the ionised air molecules, showing the trail of radiation.

Jump to other topics

1Energy

2Electricity

3Particle Model of Matter

4Atoms & Radiation

5Forces

5.1Basics of Motion

5.2Forces

5.3Effects of Forces

5.4Pressure

6Waves

7Magnetism

8Astrophysics

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