1. L/O ;- To know what causes background radiation
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What is radiation?
L/O ;- To know what causes background radiation

2. Do you have any of these detectors at home? What are they?
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Do you have any of these detectors at home? What are they?
Smoke detector
Carbon monoxide detector
Radon gas detector

3. 21/04/2017
The amount of background radiation varies considerably around Britain, as shown on the map. You can see that it is particularly high in Cornwall, because of the types of rock there
You have grown up on a planet which has, in places, quite a high level of background radiation, and life on Earth has evolved to cope with this. Your cells have self-repairing mechanisms which allow them to survive relatively unscathed.
What do you think may be different about the areas in red to give them higher background radiation?

4. Background Radiation 13% are man-made Radon gas Food Cosmic rays
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13% are man-made
Radon gas
Food
Cosmic rays
Gamma rays
Medical
Nuclear power

5. Introduction to Radioactivity
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Some substances are classed as “radioactive” – this means that they are unstable and continuously give out radiation:
Radiation
The nucleus is more stable after emitting some radiation – this is called “radioactice decay”.

6. When isotopes decay they often give out Alpha, Beta or Gamma radiation
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When isotopes decay they often give out Alpha, Beta or Gamma radiation

7. Types of radiation Unstable nucleus New nucleus Alpha particle
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Alpha Radiation ()
An alpha particle contains 2 protons and 2 neutrons (a Helium nucleus). Because the atom has lost protons, it becomes a different element (mass decreases by 4)
Unstable nucleus
New nucleus
Alpha particle
Beta Radiation ()
A Beta () particle is a high energy electron from the nucleus. When this is released, a neutron changes into a proton. This means a new atom is formed
Beta particle
New nucleus
Unstable nucleus
Gamma Radiation ()
After  or  decay, excess energy is sometimes given off. This is called Gamma radiation (wave with a high frequency and short wavelength). Because the proton number does not change, the atom remains the same
Unstable nucleus
New nucleus
Gamma radiation

8. Blocking Radiation    Sheet of paper Few mm of aluminium
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Each type of radiation can be blocked by different materials:   
Sheet of paper
Few mm of aluminium
Few cm of lead

9. Assessed Question
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Why do you think alpha radiation is the least penetrating?
Which do you think is the most dangerous outside your body? Why?
Which do you think is the most dangerous inside your body? Why?

10. Dangers of radioactivity
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Radiation will ionise atoms in living cells – this can damage them and cause cancer or leukaemia.
Alpha
Beta
Gamma
OUTSIDE the body  and  are more dangerous as  radiation is blocked by the skin.
INSIDE the body an  source causes the most damage because it is the most ionising.

11. Gamma rays / light / microwaves / radio waves / ultraviolet
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Different types of electromagnetic radiation are used for different jobs
TYPE OF RADIATION
WHAT THE RADIATION IS USED FOR
to send along optical fibres in an endoscope
to give skin a tan (but can cause cancer in cells)
to sterilise surgical instruments
to send information to and from satellites
Choose words from the list to complete the table
Gamma rays / light / microwaves / radio waves / ultraviolet

12. Complete the following.
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Complete the following.
A = B =
(c) Our bodies are exposed to gamma radiation all the time. Write down two sources of this gamma radiation.

13. A piece of rock gives a high reading with a radiation detector.
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A piece of rock gives a high reading with a radiation detector.
The diagrams show what happens when rock is wrapped in paper and aluminium foil
What type of radiation does the rock emit?
Explain your answer
You can use the rock to measure the thickness of different types of aluminium foil

14. 21/04/2017
The diagram shows what happens to the radiation from 3 radioactive substances when different materials are put in their way
Fill in the table from
Alpha / Beta / Gamma / UV
RADIOACTIVE SUBSTANCE
TYPE OF RADIATION IT EMITS A B C

15. Complete the following sentence.
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(a) Radiation can cause cancer. The graph shows that the risk of cancer depends on the radiation dose a person is exposed to.
Complete the following sentence.
The the dose of radiation a person gets, the greater the risk of cancer.

16. 5. (a) There are three types of radiation, alpha, beta and gamma.
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5. (a) There are three types of radiation, alpha, beta and gamma.
The diagram shows what can stop the radiation from two different sources.
Which type of radiation, alpha, beta or gamma is given out by:
Americium
(ii) strontium?

17. 21/04/2017
Diagram 1 shows the position of a smoke detector inside a house. Diagram 2 shows the warning label at the back of the smoke detector.
Explain why the radiation given out by the americium is unlikely to do any harm to people living in the house.

18. Explain why the americium source will never need to be replaced.
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(c) The graph shows how the number of americium atoms inside a source goes down slowly.
The battery inside the smoke detector lasts one year and is then replaced.
Explain why the americium source will never need to be replaced.