Radiation Flashcards
1
Q
Atoms are composed of
A
Protons, neutrons and electrons
2
Q
The centre of an atom is called the
A
Nucleus
3
Q
The nucleus of an atom contains
A
Protons and neutrons
4
Q
The particles in orbit around the nucleus are
A
Electrons
5
Q
Protons have a charge of
A
1+
6
Q
Neutrons have a charge of
A
0, neutral
7
Q
Electrons have a charge of
A
1-
8
Q
Protons have a mass of
A
1
9
Q
Neutrons have a mass of
A
1
10
Q
Electrons have a mass of
A
0
11
Q
Isotopes are
A
Atoms of the same element with a different amount of neutrons
12
Q
Alpha radiation is
A
A helium nucleus
13
Q
Beta radiation is
A
A fast moving electron
14
Q
Gamma radiation is
A
An electromagnetic wave
15
Q
Alpha radiation is absorbed by
A
A sheet of paper
16
Q
Beta radiation is absorbed by
A
2-3 mm aluminium
17
Q
Gamma radiation is absorbed by
A
5-6 cm lead
18
Q
Ionisation is
A
The removal or addition of an electron from an uncharged atom
19
Q
The strongest ionising radiation is
A
Alpha
20
Q
The range of alpha radiation in air is
A
A few centimetres
21
Q
The range of beta radiation in air is
A
A few meters
22
Q
The range of gamma radiation in air is
A
Infinite
23
Q
The activity of a radioactive source is
A
The number of nuclei that decay each second
24
Q
The unit of activity is
A
Becquerels Bq
25
The relationship between activity, number of decays and time is
number of decays
Activity = ————————-
Time
N
A = —
t
26
The half-life of a radioactive source is
The time taken for the activity of a source to half
27
The effect of radiation on living cells is
To kill or damage living cells
28
The biological effect of radiation depends on three factors:
Absorbed dose
Type of radiation
Type of tissue absorbing the radiation
29
Absorbed dose is
The energy absorbed per unit mass of the absorbing material
30
The unit of absorbed dose is
Grays Gy
31
The relationship between absorbed dose, energy and mass is
Energy
Absorbed dose = ————
Mass
Or
E
D = —
m
32
Equivalent dose is
A measure of the biological risk caused by radiation
33
The unit of equivalent dose is
Sieverts Sv
34
The relationship between equivalent dose, absorbed dose and radiation weighting factor is
Equivalent dose = absorbed dose • radiation weighting factor
Or
H = Dwr
35
Equivalent dose rate is
The rate at which the equivalent dose is received
36
The relationship between equivalent dose rate, equivalent dose and time is
Equivalent dose
Equivalent dose rate = ————————-
Time
Or
. H
H = —
t
37
Sources of background radiation include
Radon and Thoron gas from rocks and soil
Gamma rays from the ground
Carbon and potassium in the body
Cosmic rays
38
Detectors of radiation include
Geiger-müller tube
Spark counter
Cloud chamber
Scintillator
Film badge
39
The average annual effective equivalent dose from background radiation in the uk is
2.2 mSv
40
The annual effective equivalent dose limit for a member of the public is
1 mSv above background
41
The annual effective equivalent dose limit for a radiation worker is
20 mSv above background
42
Safety precautions when using radioactive sources include
Limit time of exposure
Store in lead lined containers
Point sources away from body (especially eyes)
Handle with tongs
Wash hands after use
43
Uses of alpha radiation include
Smoke detectors
Killing cancerous cells
44
Uses of beta radiation include
Monitoring the thickness of paper or thin metal sheets
45
Uses of gamma radiation include
Radioactive tracers
Killing cancerous cells
46
Nuclear fission is
The splitting of a large nucleus into smaller nuclei
47
Nuclear fusion is
The joining of small nuclei to form a larger nucleus
48
In a chain reaction for fission or fusion
The neutrons released when one nucleus splits go on to split further nuclei and the process then repeats
49
Nuclear fusion takes place at
Extremely high temperatures
50
Difficulties with maintaining nuclear fusion include
Plasma containment
Extracting useful heat energy from the reactions
51
Disadvantages of nuclear fission include
Produces radioactive waste
Expensive to build nuclear power stations
52
Advantages of nuclear power (fission or fusion) include
A lot of energy from a small amount of fuel
Does not produce any pollution
53
Advantages of nuclear fusion include
Does not produce radioactive waste
A lot of energy from a small amount of fuel
Does not produce any pollution
54
To experimentally determine the half-life of a radioactive source
Use a Geiger-Müller tube and counter to measure number of counts in a minute from source
Repeat this measurement at regular time intervals
Subtract the background count rate
Draw a graph of corrected count rate against time
55
How does a Geiger-Müller tube work
Electrode in the centre of tube, high voltage applied, tube is filled with gas. Radioactive source pointed into the tube ionising the gas which creates a small brief electrical charge. These pulses can be then be counted
56
How does a spark counter work
A fine metal gauze is mount about a millimetre away from a thin wire, a voltage is passed through them so sparking can occur. If alpha radiation is exposed between them, it will ionise the air creating a spark. These sparks can then be counted to measure the radiation. Beta and gamma can not be used with a spark counter as they produce insufficient ions for sparking to take place
57
How does a cloud chamber work
The space inside the chamber is filled with alcohol vapour and as a particle passes through, tiny droplets of alcohol form, showing up its track
58
How does a scintillator work
When exposed to ionisation, the material emits light when they absorb particles
59
How does a film badge work
3 different materials covering the front side of the badge, each one can absorb the next level of radiation, I.e 1 can absorb alpha radiation, 1 can absorb beta and 1 can absorb gamma. Photographic film is placed behind this and the radiation that is encountered will appear on the film
60
State one detector of gamma radiation
Photographic film
GM Tube
61
State one source of gamma radiation
Stars
Some radioactive substances (e.g. Cobalt 60)
62
State one use for gamma radiation.
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
63
What are the three types of radiation?
alpha
beta
gamma
63
What are the three types of radiation?
alpha
beta
gamma
64
Which is the least ionising radiation?
Gamma
65
What is meant by shielding?
Shielding means having something that will absorb radiation between you and the source of the radiation.
66
What is meant by background radiation?
It is the radiation that is all around us.
67
State a source of man-made background radiation.
1) Weapons testing
2) Waste from the Nuclear industry
3) Medical uses: Having an X-ray, CT scan, barium meal etc.
68
What is the radiation weighting factor?
A number that takes into account the type of radiation you are exposed to.
69
What is the link between the radiation weighting factor and the ionisation caused by a source?
The more ionisation the higher the radiation weighting factor.
