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

2. Radioactive Emissions

3. Absorption of Radiation

4. Detection of Radiation
Geiger counter
Photographic film
Cloud chamber

5. Background Radiation
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.
There are also made artificially: Medical Uses – cancer treatment, medical tracers Nuclear Industry – weapons industry, power industry

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

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

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

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

10. Choose the correct answer …
RADIOACTIVITY QUIZ
Choose the correct answer …

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

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

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

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

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

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

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

18. 8. Radioactive waste should be stored in ……
Lead boxes
Concrete bunkers
It depends on the type of radiation

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

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

21. Radioactivity
Complete the following nuclear reactions: