Radioactivity l Emission of energy from unstable nuclei which are trying to become stable l Natural effect - radioactive isotopes are found everywhere. l Radiation can cause ionisation (removal of electrons) of the atoms in our cells which can cause mutations in DNA.

Radioactive Emissions

Absorption of Radiation

Detection of Radiation l Geiger counter l Photographic film l Cloud chamber

Background Radiation l Radioactive isotopes occur naturally : Cosmic rays – we are protected from these by the atmosphere, but airline pilots receive a higher dose. Granite – contains uranium, people in Cornwall receive a higher dose than usual because there is a lot of granite there. Food, our bodies, buildings etc. l There are also made artificially : Medical Uses – cancer treatment, medical tracers Nuclear Industry – weapons industry, power industry

Uses of Radioactivity l Treating cancer l Internal inspection l Tracing l Smoke detectors l Sterilisation l Food irradiation l Thickness monitoring

Using radioactivity l The 3 types of radiation have different properties. l These properties make them useful in different situations

Examples of uses. l Smoke detectors. l Use ALPHA l Smoke present Alpha Source Detector Alpha particles reaching the detector - no alarm Alpha Source Detector Alpha particles do not reach the detector – alarm goes off

Question. l Why would Beta or Gamma radiation not be suitable in a smoke detector? l Which radiation would be most suitable for internal inspection of jet engines? l How is gamma used for sterilising syringes.

RADIOACTIVITY QUIZ Choose the correct answer …

1.Which statement is TRUE ? A. Alpha particles have a positive charge B. An alpha particle is an electron C. Alpha particles travel at the speed of light.

2.Which statement is false ? A. Radiation can be used to treat cancer B. Radiation can cause cancer C. Cancerous cells are radioactive

3.Look at the picture. The particle labelled is: A. An electron B. Postively charged C. A Gamma Ray

4.Alpha particles are dangerous because… A. They are toxic B. They can cause mutations of our DNA C. They are radioactive

5.Gamma radiation … A. Is a stream of particles called electrons B. Travels at the speed of light C. Can be stopped by 3 mm of aluminium

6.Gamma rays can be used to sterilise food because: A. They can kill bacteria B. They make the food radioactive for a short time. C. They are very strong.

7. People in Cornwall receive a higher than average radiation dose because … A. There are a lot of nuclear power stations in Cornwall B. The atmosphere is thinner there and so there is less protection from cosmic rays. C. There is a lot of granite underground in Cornwall.

8. Radioactive waste should be stored in …… A. Lead boxes lClConcrete bunkers lIlIt depends on the type of radiation

9. Which is true? A. Alpha particles only travel a few cm in air B. Alpha particles can pass through skin C. Alpha particles are given off by everything around us

10. Which is true? A. When something is hit by radiation it becomes radioactive B. Alpha and beta particles are only dangerous if they are swallowed C. Gamma radiation is the most penetrative.