RADIOACTIVITY EXPERIMENTS

THE PHYSICS SUPERMARKET
  1. Randomness of Radioactive Decay
  2. Rate of Radioactive Decay
  3. Nuclear Transformations
  4. Effects of Radiation on People
  5. Nuclear Reactors and Bombs

1. Randomness of Radioactive Decay

Students first analyse the classic random event - the number of Prussion soldiers kicked to death by their horses per year, to discover how to identify if an event is random. They then apply their findings to the decays produced by an artificial electronic source form IEC Australia. The 'Magic' source has a display and makes clicks like a real Geiger Counter.

2-12 V AC/DC power supply, IEC 'Magic' radioactive source (manufactured by Industrial Equipment and Control (Australia) 61-63 McClure Street Thornbury Victoria 3071 Australia. ph 61 3 9497 2555 fax 61 3 9497 2166.   Top

2. Rate of Radioactive Decay

This is another experiment using the artificial source. This time the source decays rapidly and the number of nuclei remaining is displayed each second. Students record the number remaining every 15 secs for about 3 minutes. They calculate the decay rate and discover it is proportional to the number remaining. The source is programmed to have a decay constant of 1 unit and this enables the students to discover by trial and error the equation that calulates the number remaining with time. They discover the existance and find a value for the exponential number e. They use their equation to predict how long it will take the source to decay to 1 remaining and check their prediction with the source. It takes about 46 mins to decay from an initial 1020 radioactive nuclei to 1 remaining.

2-12 V AC/DC power supply, IEC 'Magic' radioactive source  Top

3. Nuclear Transformations

In this theoretical exercise the properties and energy transfers of alpha, beta and gamma decay are discussed. The eV unit of energy is defined. Students write the equations of the different decays and draw pictures to illustrate them. Decay chains and artificial transmutation are also discussed.

No equipment required  Top

4. Effects of Radiation on People

In this theoretical exercise, the different methods of measuring the level of exposure is explained Students learn how to calculate the Absorbed Dose in Gray and the Absorbed Dose Equivalent in Sievert by the body, and the Effective absorbed Dose Equivalent of organs. The effects that different doses have on people are described.

No equipment required  Top

5. Nuclear Reactors and Bombs

Students investigate the mass difference between a uranium nucleus and the total mass of the individual protons and neutrons. The concept of binding energy is defined and its value calculated for Uranium using the equation E = mc2. The formation of two intermediate sized nuclei instead of the one big Uranium nucleus is investigated and the students find that energy would be released if a Uranium atom was split. Chain reactions and harnessing the chain reaction is discussed. The structure of a typical nuclear reactor is discussed.

No equipment required  Top