GCSE Physics · AQA 8463 · Topic 4.4.3
Hazards and uses of radioactive emissions and of background radiation
Key points
- Background radiation comes from natural sources (rocks such as granite, radon gas, cosmic rays) and man-made sources (fallout from weapons tests, nuclear accidents).
- Radiation dose is measured in sieverts (Sv), often millisieverts (mSv). Dose depends on job and location.
- The hazard of a source depends on its half-life: a short half-life gives a high activity quickly but soon falls; a long half-life stays a hazard for a long time.
- Inside the body alpha is most dangerous (very ionising); outside the body alpha is blocked by skin, so beta and gamma are more harmful.
- Medical uses: gamma or beta tracers to explore organs (short half-life, low ionisation), and radiotherapy to destroy tumours.
- Results about radiation risks are peer reviewed before being accepted.
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We are exposed to a small amount of radiation all the time, and doctors deliberately use radiation to diagnose and treat disease. This sub-topic is about judging those risks: where background radiation comes from, how dose is measured, why…
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