Ionising Radiation
Quantum and Nuclear

Making links

Teaching Guidance for 14-16 Supporting Physics Teaching

Making links between different representations

A key part of learning physics involves making links between different representations. This is certainly the case for radioactive decay. In building up a picture and understanding of radioactive decay, students are required to move between a range of different representations.

  • The physical process: students watch a demonstration carried out by the teacher of the decay of a radioactive source (with a short half-life). They become aware of the falling off in the counting of the Geiger–Müller tube: steeply at first and then more slowly.
  • A graphical representation: the students plot a graph of the activity of the source against time.
  • A physical model: the students work with a dice model of radioactive decay.
  • A mental model: the teacher encourages students to visualise a stockpile consisting of two colours of balls. Over time, one colour changes to another.
  • A mathematical model: the students carry out calculations based on the constant fractional decay of the radioactive source.

Meaningful learning by students comes about when they are able to link, and move easily between, all of these processes, models and representations.

Ionising Radiation
is used in analyses relating to Radioactive dating
can be analysed using the quantity Half-Life Decay Constant Activity
features in Medical Physics

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