The early workers with radioactivity
found that it could produce ions in a gas and this property has been used in all of the detectors of
radiation. It is also the reason why radioactivity can be dangerous. You can show this ionising
effect using the following simple experiment.
[TO BE DONE ONLY
BY YOUR TEACHER]
Remove the glass side of a gold leaf electroscope and charge the
electroscope with a polythene rod. Then hold a radium source near the leaf. The leaf will go down
slowly showing that the charge has leaked away through the ions in the air. These ions have been
made by the radioactivity passing through it.
(Using a match instead of the source will
have the same effect and you should have seen that burning a match in air between two charged
plates ionises the air between them and gives a current between the plates).
