Radioactive Decay

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

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.

ionising radiation enters a tube full of low pressure gases. it ionises the atom in the gas, knocking electrons out of the atoms. the gas can now conducts 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.