1. P2 Radiation from Rocks pt2 Revision Mock 2015

2. Uses of Nuclear Radiation

3. Irradiation of Food: Radiation can destroy microorganisms that cause food spoilage.

4. Uses of Beta Radiation

5. Uses of alpha particles –Smoke Detector

6. Background radiation
Radiation is all around us, much of it originating from natural sources, including:
animals
soil and plants
rocks
cosmic rays.
Teacher notes
Background radiation mainly comes from rocks and cosmic rays (radiation that reaches the Earth from outer space).
Image credits: pig © Michaela Stejskalova; plant © arteretum; rocks © nito; Earth © argus, all Shutterstock.com 2011
Radiation can come from man-made sources such as industrial and hospital waste. The fallout from nuclear accidents and nuclear weapons testing also releases radiation.

7. How can radiation be detected?
Boardworks GCSE Science: Physics
Radioactivity
Radioactivity cannot be seen, it has no smell and does not make any sound. However, the effects of radiation can be detected and measured using instruments such as Geiger–Müller tube.
When connected to a ratemeter, the GM tube gives a reading in ‘counts per second’ and a loudspeaker ‘clicks’ for each particle, or burst of radiation, detected.
Teacher notes
For best results, it is recommended that the video is viewed with a screen resolution of 1024 × 768 and colour quality set to 32 bit (in Control Panel, Display, Settings).
A GM tube is filled with argon gas, and around +400 V are applied to a thin wire in the middle. When a particle enters the tube, it removes an electron from an argon atom. The electron is attracted to the central wire, and as it rushes towards the wire, it knocks other electrons from argon atoms, causing an ‘avalanche’. One single incoming particle will therefore cause many electrons to arrive at the wire, creating a pulse that can be amplified and counted. This makes a GM tube a very sensitive detector.
It is the darkening effect of radiation on photographic film that led to the discovery of radioactivity over 100 years ago.
Video credit: © 2011 Shutterstock.com
Reading radiation levels outside Reactor 4 of Chernobyl nuclear power plant on December 16th, 2007
Radioactivity can also be detected by photographic film, which darkens when it absorbs radiation. 7

8. Sources of background radiation

9. Measuring the corrected count rate (activity)