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Harry's National 5 Physics > Radiation > Flashcards

Radiation Flashcards

1
Q

State one detector of gamma radiation

A
  • Photographic film
  • GM Tube
  • Bubble chamber
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2
Q

State one source of gamma radiation

A
  • Stars
  • Some radioactive substances (e.g. Cobalt 60)
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3
Q

State one use for gamma radiation.

A
  • Used as a tracer in medicine
  • Used to treat cancer
  • Sterilisation of operating instruments
  • In industry, radioactive “tracer” substances can be put into pipes and machinery, then we can detect where the substances go.
  • Gamma rays kill microbes, and are used to so that it will keep fresh for longer. This is known as “irradiated” food.
  • Checking for cracks in aeroplane wings and joints
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4
Q

What are the three types of radiation?

A
  • alpha
  • beta
  • gamma
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5
Q

What is the radiation known as alpha particles?

A

It is a helium nucleus.

(It has 2 protons and 2 neutrons.)

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6
Q

What is the radiation known as beta radiation?

A

It is a fast moving electron from the nucleus.

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7
Q

What is the radiation known as gamma radiation?

A

It is a high energy / frequency wave and part of the electromagnetic spectrum.

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8
Q

What is meant by ionisation?

A

It is when an atom gains or loses an electron to become charged.

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9
Q

Which is the most ionising radiation?

A

alpha

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10
Q

Which is the least ionising radiation?

A

Gamma

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11
Q

State three detectors of radiation.

A
  1. Photographic film
  2. GM Tube
  3. Scintillation counter
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12
Q

What will absorb alpha radiation?

A

A few centimetres of air or a sheet of paper.

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13
Q

What will absorb beta radiation?

A

A few millimetres of aluminium

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14
Q

What will absorb gamma radiation?

A

Several centimetres of lead

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15
Q

What is meant by shielding?

A

Shielding means having something that will absorb radiation between you and the source of the radiation.

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16
Q

What will the amount of shielding required depend on?

A

The amount of shielding required to protect against different kinds of radiation depends on how much energy they have.

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17
Q

How can you reduce your exposure to radiation when you are working with it?

A
  • Limit the time you have the source out (only get it when you need it)
  • Handle only using tongs
  • Keep the source at arm’s length
  • Wash hands before and after use
  • Do not eat while handling it
  • Wear lead lined gloves/apron and safety goggles
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18
Q

What is meant by background radiation?

A

It is the radiation that is all around us.

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19
Q

State a source of man-made background radiation.

A

1) Weapons testing
2) Waste from the Nuclear industry
3) Medical uses: Having an X-ray, CT scan, barium meal etc.

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20
Q

State a source of natural background radiation.

A

1) Rocks: Some rocks such as granite or pitchblende are high in radioactivity
2) Food: Food can be slightly radioactive because of the soil it has been grown in.
3) Body: Contains Potassium 40 which is radioactive.
4) Cosmic Rays: Radiation from the Sun and outer space. The atmosphere will absorb most of this.
5) Radioactive gases: Radon and Thoron gases make up most of the dosage you will receive from background radiation. The gases come from rocks underground and the amount you are exposed to depends on the geology of where you live.

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21
Q

What is meant by absorbed dose?

A

The energy absorbed per unit mass

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22
Q

What is equivalent dose?

A

It is a way of taking into account the absorbed dose and the type of radiation you are exposed to.

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23
Q

What is the radiation weighting factor?

A

A number that takes into account the type of radiation you are exposed to.

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24
Q

What is the link between the radiation weighting factor and the ionisation caused by a source?

A

The more ionisation the higher the radiation weighting factor.

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25
Q

What is meant by equivalent dose rate?

A

Equivalent dose absorbed per unit time.

26
Q

Give at least 2 uses for radiation.

A
  • Gamma rays are used for radiotherapy which is a cancer treatment
  • Thickness control of paper or metal sheet for example.
  • Gamma radiation can be used to sterilise medical instruments
  • Radio-carbon dating
  • Tracers - can be used in industry in pipes to look for cracks or in the human body to check for blockages
27
Q

What is meant by the activity of a source?

A

It is the number of decays/disintegrations per second

28
Q

What is meant by the half-life of a source?

A

It is the length of time it takes for the activity of a source to drop to half of it’s original value.

29
Q

Describe how to calculate the half-life of a source from a graph.

A

* Choose a ‘nice’ starting value e.g. 20,000Bq.

  • Find the ‘time’ that this happens at e.g. 0 Hours.
  • Once a half life has passed the activity will be 20,000÷2 = 10,000Bq.
  • Find the time that this happens at from the graph – 12 Hours.
  • Calculate the time for the change is 12 – 0 = 12 hours
30
Q

What is meant by fission?

A

Fission is when a nucleus of a large mass number splits into two nuclei of smaller mass numbers, with the release of energy and neutrons.

31
Q

What is meant by fusion?

A

Fusion is when two nuclei of smaller mass number combine to form a nucleus of larger mass number.

32
Q

What is the fuel in a nuclear fission reactor?

A

Uranium

33
Q

How does a nuclear fission power station produce electrical energy?

A
  • The nuclear reactor uses fission of Uranium to produce large amounts of heat energy.
  • The heat energy is used to heat water.
  • The water which is heated, turns into steam, is piped to turn a turbine.
  • The steam makes the turbine turn. (Heat energy to Kinetic Energy)
  • The turbine turns the generator to create electrical energy. (Kinetic to Electrical energy)
34
Q

Give an advantage of producing electricity using a nuclear fission reactor.

A
  • Do not produce greenhouse gases – Carbon dioxide, methane, nitrous oxide
  • Do not rely on fossil fuels which are in short supply
  • Huge amount of energy from a small amount of fuel
  • Small amount of waste produced
  • Reliable source of energy (Unlike solar or wind)
35
Q

Give a disadvantage of producing electricity using a nuclear fission reactor.

A
  • The waste produced is radioactive. It has to be stored safely for a long time.
  • Uranium is a non-renewable fuel.
  • Risk of radioactive materials being released into the environment if there is an accident.
  • Expensive to decommission nuclear power stations at the end of their useful life.
36
Q

What are the products in a fission reaction in a nuclear reactor.

A
  • fission fragments (smaller mass nucleii)
  • Heat energy
  • More neutrons
37
Q

What are the particles in the nucleus called?

A

Protons and neutrons

38
Q

What is the charge on a proton?

A

Positive

39
Q

What is the charge on a neutron?

A

No charge

40
Q

What is the charge on an electron?

A

Negative

41
Q

In an atom which particle orbits the nucleus?

A

Electron

42
Q

What are the main parts of an atom?

A

See diagram

43
Q

What is the charge on an alpha particle?

A

Positive

44
Q

What is the charge on a beta particle?

A

Negative

45
Q

What is the charge on a gamma ray?

A

No charge

46
Q

What precautions should be taken when storing a radioactive source?

A
  • Source should be clearly labelled as to type
  • Stored in lead lined boxes
47
Q

What is meant by a corrected count rate?

A

It is when the background radiation is subtracted from the radiation measured so that the reading is caused by the source not background radiation.

48
Q

Which line on the graph represents the corrected count rate? Give a reason for your answer.

A

It is the dotted red line.

You know this is the corrected reading as it is lower than the other reading as background has been subtracted.

This graph gives a 0 reading for the count rate, this is not possible as there is always background radiation so must be the corrected graph.

49
Q

What is the annual effective dose of the average annual background radiation in the UK?

A

2.2mSv

50
Q

What is the annual effective dose limit for a member of the public?

A

1mSv

51
Q

What is the annual effective dose limit for a radiation worker?

A

20mSv

52
Q

What is the impact of ionisation on living cells?

A

It can kill them.

53
Q

State one method of monitoring exposure to radiation.

A

Radiation film badge.

54
Q

Explain how a radiation film badge is used to monitor the exposure to radiation.

A
  • Badge has several windows in it made from different materials - when the film is developed the type of radiation can be identified by which windows have been penetrated by the radiation
  • The darker the film behind the windows the more radiation the badge has been exposed to.
55
Q

State the equipment you would need to measure the half life of a source.

A
  • Timer
  • G-M Tube and counter
  • Source of radiation
56
Q

Explain an experiment to measure the half life of a source.

A
  • With no source present record the number of counts in one minute using the G-M tube and counter. This is the ‘background radiation’.
  • Put source in position. The stop clock and the counter are started at the same time.
  • Take a reading of the counts per minute every minute. Do this for 10 minutes.
  • The background radiation is subtracted from each of the readings so that the counts / minute for the source are recorded.
  • A graph is plotted of counts / minute against time. The half-life is calculated from the graph.
57
Q

Where does the energy come from in a fission and a fusion reaction?

A

Some of the mass is converted into energy.

58
Q

What is meant by a chain reaction?

A

A chain reaction is when a neutrons causes fission and releases more neutrons. The neutrons produced in the fission reaction, go on to cause their own fission reactions.

59
Q

State 2 issues that must be overcome in fusion reactors.

A
  1. The high temperatures required
  2. The high pressures required
60
Q

Why is containment an issue for fusion reactors?

A

The high temperatures of the plasma would vapourise any materials that we currently know.

61
Q

State an advantage of a fusion reactor.

A
  • Releases massive amounts of energy
  • It is sustainable (unlikely to run out)
  • No greenhouse gases
  • No risk of meltdown
62
Q

Explain how a fusion reactor could generate electrical energy.

A
  • At high temperature and pressure small nuclei join together
  • This releases huge amounts of heat energy (Nuclear to Heat)
  • The heat energy is used to heat water to steam.
  • The steam is used to turn a turbine. (Heat to Kinetic)
  • The turbine is used to turn a generator. (Kinetic to Electrical)

Harry's National 5 Physics (8 decks)

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