Detection of Radiation
Physics: AQA GCSE Higher, topic 4.2.3
Detecting Radioactivity
There are three primary ways of detecting radioactivity.
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.
Photographic film
- Ionising radiation has the same effect on photographic film as light.
- A bright spot appears wherever the ionising radiation hits the film.
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.
Test yourself on Detection of Radiation
How does photographic film detect radiation?
Geiger Counter