Activity and half-life calculations
I can interpret radioactive half-life graphs and make calculations using values of half-life.
Activity and half-life calculations
I can interpret radioactive half-life graphs and make calculations using values of half-life.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- The amount (or activity) of a radioactive isotope repeatedly falls by half in equal amounts of time.
- A radioactive half-life graph shows the amount (or activity) of a radioactive isotope plotted against time.
- In 2 half-lives the amount (or activity) of a radioactive isotope falls to ½ × ½ = ¼ as much.
- In 3 half-lives the amount (or activity) of a radioactive isotope falls to ½ × ½ × ½ = 1/8 as much, and so on.
- Radioactive isotopes with short half-lives decay quickly, emitting most radiation over a short period of time.
Keywords
Activity - the number of decays per second; it is measured in becquerels (Bq)
Radioactive isotopes - contain unstable nuclei that will decay over time and emit ionising radiation
Radioactive half-life - the time taken for the activity of a sample of a radioactive isotope to halve
Common misconception
It is impossible to predict outcomes for random events such as radioactive decay.
Use analogies to show that random nuclear decay can lead to predictable outcomes, such as the randomness in the order popcorn kernels pop, but the predictability of how quickly all the popcorn takes to cook.
To help you plan your year 11 physics lesson on: Activity and half-life calculations, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 11 physics lesson on: Activity and half-life calculations, download all teaching resources for free and adapt to suit your pupils' needs.
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Explore more key stage 4 physics lessons from the Nuclear physics unit, dive into the full secondary physics curriculum, or learn more about lesson planning.
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Adult supervision recommended
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