The same radiation that can harm is, used carefully, a precise tool. The trick is matching the radiation type and the half-life to the job, alpha for a smoke alarm, gamma to sterilise, a short-lived tracer for the body.
The use of a radioactive isotope is matched to its radiation type and half-life. Smoke alarms use alpha, sterilising equipment and treating cancer use gamma, medical tracers use short-lived sources, and thickness gauges use beta.
Radioactive isotopes are chosen for a use by matching their radiation type and half-life to the job.
A medical tracer needs a short half-life so it does not stay radioactive in the body for long.
Pick the radiation and half-life for each application and see why it fits.
Four quick checks. Each correct answer earns XP and lights this skill on your star map.
A smoke alarm uses a source that emits...
Sterilising medical equipment uses...
A radioactive tracer used inside the body should have...
Monitoring the thickness of metal foil during manufacture uses...
Each use needs a particular penetrating power and a suitable half-life.
| Use | Suitable source |
|---|---|
| Smoke alarm | Alpha, which ionises the air over a short range |
| Sterilising equipment and treating cancer | Gamma, which is penetrating |
| Medical tracer in the body | A short half-life so it soon stops being radioactive |
| Thickness monitoring of foil | Beta, which is partly absorbed by the material |
Each use needs the right radiation and half-life. A medical tracer needs a short half-life so it does not stay radioactive in the body, while a smoke alarm uses alpha because it ionises the air over a short range.
Unlocks once the four checks above are done. Worth more XP, written in the style of Paper 2.
Why is a gamma source, rather than alpha, used to sterilise sealed medical equipment?
A radioactive substance is injected as a tracer to follow blood flow. The best choice has...
In a paper mill, a beta source and detector monitor paper thickness because...
Applications of radioactivity are mapped. Keep the chain going.