Atoms and nuclei > ionisation

This demonstration shows how a circuit can be set up to detect a familiar event that produces ions. A simple circuit with a beaker of water can be made to conduct by adding a heap of salt. This is a useful step towards understanding the spark counter and the Geiger-Müller tube.

The Van de Graaff generator always produces excitement for students.

An EHT supply can be used to produce sparks, which can be increased if you add a capacitor in parallel with the air gap. You can use the sparks to count matches. Use this to develop the ideas behind the spark counter and, eventually, the Geiger-Müller tube.

This ‘match counter’ is a useful step towards understanding a Geiger-Müller tube.