Episode 513: Preparation for exponential decay topic
In this section, we are not concerned with the products of radioactive decay. Rather, we are
looking at the random, spontaneous nature of radioactive decay and its consequences.
The key problems students have are (i) thinking erroneously that after two half lives, everything is
over, and (ii) understanding the connection between what individual nuclei do, and how a large
sample of radioactive nuclei behave.
Depending upon the specification you are following, some of the material is part of the
first year or the second year of post-16 level course. You will need to adjust the level of
mathematics accordingly.
Episode 514: Patterns of decay
Episode 515: The radioactive decay formula
Episode 516: Exponential and logarithmic equations
Main aims
Students will:
1. Define the term half-life.
2. Make calculations involving numbers of half-lives.
3. Relate half-life to decay probability .
4. Measure the half-life of a fast-decaying nuclide.
5. Use exponential and logarithmic equations for radioactive decay.
Prior knowledge
Basic, descriptive radioactivity should already have been covered. Students will have previously
been introduced to the term half-life, but are unlikely to be confident in using the quantity in
calculations.
Where this leads
The mathematics of exponential decay parallels that of capacitor discharge, damped SHM etc, so
these would be suitable topics to tackle next. If students have already met these topics, you could
usefully spend time drawing the parallels between them.
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