P7

What are the three types of radiation?
Alpha, Beta and Gamma
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What is alpha radiation made up of?
Positively charged particles
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What investigation was carried out with alpha particles?
Beam of them directing at metal foil
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What happened in the investigation?
Some alpha particles rebounded from the foil
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What did this prove?
The nucleus is positively charged
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What is an unstable nucleus?
Decays when it emits radiation
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What is decaying?
A random event that happens without anything being done to nucleus
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How does a nucleus between stable or less unstable?
By emitting alpha, beta or gamma
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Why was the plum pudding model disregarded?
It could not explain why alpha particles were scattered through large angles
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What did Bohr discover?
Electrons orbit nucleus at specific distances and specific energy values or energy levels
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What are isotopes?
Are atoms of the same element with different numbers of neutrons
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What is the symbol for alpha?
*
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What happens when an unstable nucleus emits an alpha particle?
Its atomic number goes down by 2 and mass number goes down by 4
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What is the decay of? *
*
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What is the symbol for Beta?
*
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What happens when an unstable nucleus emits a beta particle?
The atomic number goes up by 1 and mass number is unchanged
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What is the decay of?*
*
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What absorbs alpha?
Paper
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What absorbs beta?
Aluminium sheet
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What absorbs gamma?
Thick lead sheet
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How can you measure the count rate from the source alone?
Measure count rate without source present and then measure with source
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How to test absorber materials?
Place each material between counter and soruce, measure count rate add more layers of material until count rate is zero
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What is a danger of radioactive atoms?
They ionise atoms
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When an atom is exposed to ionising radiation, what it this known as?
Irradiation
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What is radioactive contamination?
Unwanted presence of materials containing radioactive atoms on other materials
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How to reduce ionising radiation exposure?
Keeping as far away as possible, as little time as possible and shielding themselves
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What is the activity?
The number of unstable atoms in the source that decay per second
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What is half life?
The average time taken for the count rate to fall by half
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What is the formula for count rate?
*
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How is radioactive tracers used?
To trace the flow of a substance through an organ
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Why is radioactive iodine used for this test?
Its half life is 8 days, emits gamma and decays into a stable prodcut
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What are gamma cameras used for?
Taking picture of internal organs
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What does a patient do before a gamma image?
Patient injected with gamma, which is absorbed by organ
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How else can gamma be used?
In destroying cancerous tumours
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What else can destroy cancer cells in a tumour?
Radioactive implant
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What happens when a nucleus undergoes fission?
It releases 2 or 3 neutrons at high speeds and releases energy in the form of gamma plus KE
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What is shown in the diagram?*
A chain reaction
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What is shown in the diagram?
A chain reaction in a nuclear reactor
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What is the purpose of water inside a nuclear reactor?
It acts as a moderator because it slows down fission neutrons
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What do control rods do?
Absorb super-plus neutrons
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What is nuclear fusion?
Two small neucli release energy when fused together to form a single larger nucleus
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What is shown in the diagram?*
A nuclear fusion reaction
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What is shown in the diagram?*
Fusion reactions in the sun
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What happens in a fusion reaction?
The plasma is heated by passing an electric current through it and the plasma is contained by a magnetic field do that it doesn't touch the reactor walls.
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How could fusion reactors be used in the future?
Because the fuel is easy available, reaction product helium is non radioactive and the energy released for electricity
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What is the main cause of background radiation?
Radon gas
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After fuel rods are removed what has to be done?
Stored in big tanks of water
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What could new nuclear reactors have?
Standard design to reduce costs, longer operating time, safety features and less environmental effect
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Other cards in this set

Card 2

Front

What is alpha radiation made up of?

Back

Positively charged particles

Card 3

Front

What investigation was carried out with alpha particles?

Back

Preview of the front of card 3

Card 4

Front

What happened in the investigation?

Back

Preview of the front of card 4

Card 5

Front

What did this prove?

Back

Preview of the front of card 5
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