P4 - Radiation For Life Flashcards

1
Q

P4 - Radiation For Life

Which direction do electrons move when a polythene rod is rubbed with a duster?

A

From duster to rod

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2
Q

P4 - Radiation For Life

Which direction do electrons move when an acetate rod is rubbed with a duster?

A

From rod to duster

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3
Q

P4 - Radiation For Life

What is a static charge caused by?

A

Electrons moving

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4
Q

P4 - Radiation For Life

What happens if enough static charge builds up?

A

It can suddenly move which can cause sparks or shocks that may be dangerous.

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5
Q

P4 - Radiation For Life

How can a charged conductor be discharged safely?

A

By connecting it to earth with a metal strap (earthing).

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6
Q

P4 - Radiation For Life

How does earthing work?

A

Electrons flow down strap to ground if charge is negative and flow up strap from ground if positive.

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7
Q

P4 - Radiation For Life

What are ions?

A

Atoms or molecules with a charge

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8
Q

P4 - Radiation For Life

How does static attract dust?

A

Dust particles are charged and attract opposite charge. Objects in home are insulators (get easily charged) and attract dust.

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9
Q

P4 - Radiation For Life

How does static affect clothing?

A

When synthetic clothes dragged (head or other clothes) electrons scrape off, leaving static charge - two attract. Little sparks/shocks as charges rearrange themselves.

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10
Q

P4 - Radiation For Life

What causes shocks from door handles?

A

Walking on nylon carpet with insulating soles builds up charge. Touching metal door handle/water pipe allows charge to flow via conductor - little shock.

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11
Q

P4 - Radiation For Life

How can static on clothing become dangerous?

A

Charge may become large enough to make a spark - dangerous near inflammable gases or fuel fumes.

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12
Q

P4 - Radiation For Life

When can static become dangerous (other than on clothes)?

A

Fuel flowing out of pipe, paper drags on rollers or grain shoots out of pipe, static builds up. If too big, might spark - explosion in dusty/fumey places (petrol station).

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13
Q

P4 - Radiation For Life

What kind of places is static dangerous in?

A

Areas with inflammable liquids or a high concentration of oxygen (hospital operating theatre)

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14
Q

P4 - Radiation For Life

How do anti-static sprays work?

A

Make surface of a charged object conductive - provides an easy path for charges to move away.

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15
Q

P4 - Radiation For Life

How do insulating mats and shoes work?

A

Prevent static electricity moving through them - stops human getting shocked.

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16
Q

P4 - Radiation For Life

How do paint sprayers work?

A

Spray gun charged and object given opposite to attract. Paint drops repel each other (fine spray).

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17
Q

P4 - Radiation For Life

What is the good thing about electrostatic paint sprayers?

A

Method gives even coat and hardly any paint wasted. No shadows - everywhere covered.

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18
Q

P4 - Radiation For Life

How do dust precipitators work?

A

Smoke particles reach chimney bottom, meet wire grid/rods with high voltage and (-) charge. Dust particles gain electrons (become (-)) Dust particles induce charge on earthed metal plates Dust attracted to metal plates - stick forming larger particles When heavy enough, particles fall off/knocked off with hammer Falls and is removed

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19
Q

P4 - Radiation For Life

How does a defibrillator work?

A

2 paddles to power supply: Paddles firmly on chest (good electrical contact) and charged up Everyone moves away - operator holds insulated handles Charge passes through paddles to patient - heart contracts.

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20
Q

P4 - Radiation For Life

If you increase the voltage….

A

more current will flow

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21
Q

P4 - Radiation For Life

If you increase the resistance…

A

less current will flow (or more voltage is needed to keep same current flowing)

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22
Q

P4 - Radiation For Life

Current only flows when?

A

As long as there is a complete loop - broke circuit means no current.

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23
Q

P4 - Radiation For Life

What does the live wire do?

A

Carries voltage. Alternates between a high + and - voltage of about 230V

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24
Q

P4 - Radiation For Life

What colour is the live wire?

A

Brown

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25
# P4 - Radiation For Life What does the earth wire do?
Works together with fuse for safety
26
# P4 - Radiation For Life What does the neutral wire do?
Completes tcircuit - electricity flows out through neutral - always at 0V.
27
# P4 - Radiation For Life What colour is the neutral wire?
Blue
28
# P4 - Radiation For Life What colour is the earth wire?
Green and yellow
29
# P4 - Radiation For Life What must all appliances with metal cases be?
earthed
30
# P4 - Radiation For Life What does double insulated mean?
If appliance has casing that is non-conductive (e.g. plastic) - doesn't need earthing (never live)
31
# P4 - Radiation For Life What happens is a fault develops where the live wire touches the metal case?
A big current flows through live wire. Surge blows fuse and causes wire inside to melt. Cuts off live supply by breaking circuit.
32
# P4 - Radiation For Life When the fuse blows, what does this prevent?
Electric shocks by isolating appliance. Stops flex overheating which may cause fire. Prevent further damage to appliance.
33
# P4 - Radiation For Life What is a circuit breaker?
Works like a fuse but can be reset and used again.
34
# P4 - Radiation For Life How should fuses be rated?
As near as possible but just higher than normal operating current.
35
# P4 - Radiation For Life What are the fixed fuse ratings?
3A, 5A and 13A
36
# P4 - Radiation For Life What is a variable resistor?
Rheostat - resistor whose resistance can be changed by turning a knob.
37
# P4 - Radiation For Life What are variable resistors good for?
Alternating the current flowing through a circuit. Turn up resistance, current drops (vice versa).
38
# P4 - Radiation For Life Why do thinner wires increase resistance?
Electric charge has less space to move through.
39
# P4 - Radiation For Life What is the resistance of a fixed resistor like?
Steady - at a constant temperature
40
# P4 - Radiation For Life How is resistance calculated?
Voltage / current
41
# P4 - Radiation For Life How is the ammeter set up in a circuit to measure resistance?
In series with other components
42
# P4 - Radiation For Life How is the voltmeter placed in a circuit to measure resistance?
In parallel around component being tested.
43
# P4 - Radiation For Life What is the official name for voltage around a test circuit?
Potential difference
44
# P4 - Radiation For Life What are compressions?
Parts of a wave under high pressure (lots of particles)
45
# P4 - Radiation For Life What are rarefactions in a wave?
Parts under low pressure (fewer particles)
46
# P4 - Radiation For Life What is wavelength?
A full cycle of a wave from crest to crest/compression to compression
47
# P4 - Radiation For Life What is frequency?
How many complete waves there are per second passing a certain point. Measured in hertz. Sound - high frequency=high pitch
48
# P4 - Radiation For Life What is amplitude?
Measured from rest position to crest. Tells you how much energy wave is carrying, or how loud it is.
49
# P4 - Radiation For Life How does a longitudinal wave move?
Vibrations are along same direction as wave is travelling
50
# P4 - Radiation For Life How does a transverse wave move?
Vibrations are at 90 degrees to direction of travel of the wave
51
# P4 - Radiation For Life What is ultrasound?
Electric devices can be made which produce electrical oscillations of any frequency. Easily converted into mechanical vibrations to produce longitudinal waves beyond range of human hearing.
52
# P4 - Radiation For Life How does ultrasound work when breaking down accumulation in the body?
Removing kidney stones. High energy of ultrasound at stone turns it into sand like particles. Particles pass out of body in urine. Doesn't need surgery and painless.
53
# P4 - Radiation For Life How does ultrasound work in body scanning?
Waves pass through body but are reflected back when they meet a boundary between two different media. Echoes are processed by computer to produce video image.
54
# P4 - Radiation For Life What advantages does ultrasound have?
Ultrasound is great for imaging soft tissue. Safer doesn't damage cells.
55
# P4 - Radiation For Life What do X-rays do compared to ultrasound?
Better for viewing bone. Can damage living cells by being ionising radiation, causing cancer at high doses.
56
# P4 - Radiation For Life What are radioactive materials made up of?
Atoms with unstable nuclei that naturally decay at random
57
# P4 - Radiation For Life What happens as radioactive material decays?
Give out alpha, beta and gamma. Nucleus often changes into new element.
58
# P4 - Radiation For Life What is the relative atomic mass number?
Top number = number of protons and neutrons (AKA mass number)
59
# P4 - Radiation For Life What is the atomic number?
Number of protons
60
# P4 - Radiation For Life What is an isotope?
Atoms of same element with different mass numbers
61
# P4 - Radiation For Life When does gamma radiation happen in decay?
After alpha and beta, if nucleus has extra energy to get rid of. Emits gamma ray that has no mass or charge - atomic and mass number don't change.
62
# P4 - Radiation For Life What is an alpha particle?
Helium nucleus of two protons and two neutrons
63
# P4 - Radiation For Life What charge does an alpha particle have?
+2
64
# P4 - Radiation For Life What mass does an alpha particle have?
4
65
# P4 - Radiation For Life What happens to the mass number when a nucleus emits an alpha particle?
Decreases by 4 because it loses 2 protons and 2 neutrons
66
# P4 - Radiation For Life What happens to the atomic number when the nucleus emits an alpha particle?
Decreases by 2 because it has 2 less protons
67
# P4 - Radiation For Life What is a beta particle?
Fast moving electron
68
# P4 - Radiation For Life What charge does a beta particle have?
-1
69
# P4 - Radiation For Life What mass does a beta particle have?
0
70
# P4 - Radiation For Life What happens to the mass number when a nucleus emits a beta particle?
Doesn't change - lost a neutron but gained a proton
71
# P4 - Radiation For Life What happens to the atomic number when a nucleus emits a beta particle?
Increases by 1 - has 1 more proton
72
# P4 - Radiation For Life What happens as more unstable nuclei decay?
Radioactivity of the source as whole decreases - older a resource, less radiation emitted.
73
# P4 - Radiation For Life What is the problem with trying to measure how quickly radioactive material decays?
Activity never reaches 0
74
# P4 - Radiation For Life What is the definition of half life?
Time taken for half of the radioactive nuclei now present to decay.
75
# P4 - Radiation For Life What does a short half life mean?
Activity falls quickly because lots of nuclei decay in a short time.
76
# P4 - Radiation For Life What does a long half life mean?
Activity falls slowly, because most of nuclei doesn't decay for a long time.
77
# P4 - Radiation For Life What causes ionisation?
When some materials absorb ionising radiation - can enter living cells and interact with molecules.
78
# P4 - Radiation For Life What does ionisation produce?
Charged particles called ions
79
# P4 - Radiation For Life What is nuclear radiation and X-rays types of?
Ionising radiation
80
# P4 - Radiation For Life What can X-rays and gamma rays do to electrons?
Transfer energy to electrons. Electrons then have enough energy to escape from atom, ionising it and leaving it positively charged.
81
# P4 - Radiation For Life What can beta particles do to electrons?
Remove electrons from atom/molecule leaving them positively charged.
82
# P4 - Radiation For Life What happens if a beta particle sticks to an atom?
Ionises it making it negatively charged.
83
# P4 - Radiation For Life What can alpha particles do to electrons in an atom?
Remove electrons, making atom positive.
84
# P4 - Radiation For Life Why are alpha particles good ionisers?
1. Relatively large - easy to collide with atoms or molecules 2. Highly charged - easily remove electrons from atoms they pass or collide with.
85
# P4 - Radiation For Life What do lower doses of ionising radiation tend to cause?
Minor damage without killing cells. Can give rise to mutant cells which divide uncontrollably - cancer.
86
# P4 - Radiation For Life What can high doses of ionising radiation tend to do?
Kill cells completely, which causes radiation sickness if a lot of cells all get blasted at once.
87
# P4 - Radiation For Life Which types of radiation are most dangerous outside the body?
Beta and gamma - can still get to delicate organs (pass through skin)
88
# P4 - Radiation For Life Why is alpha not dangerous outside the body?
It can't penetrate the skin
89
# P4 - Radiation For Life Which source of radiation is most dangerous inside the body?
Alpha - do all their damage in a localised area, highly ionising.
90
# P4 - Radiation For Life What sources of radiation are les dangerous inside the body?
Beta and gamma - less ionising, often pass straight out with very little damage
91
# P4 - Radiation For Life What level of frequency do X-rays and gamma rays have?
High frequency
92
# P4 - Radiation For Life What distance wavelength do X-rays and gamma rays have?
Short wavelength electromagnetic waves
93
# P4 - Radiation For Life How are gamma rays made?
Released from some unstable atomic nuclei when they decay. No way to control when they are released.
94
# P4 - Radiation For Life How are X-rays produced?
By firing high speed electrons at a heavy metal like tungsten. Much easier to control production of than gamma.
95
# P4 - Radiation For Life What can X-rays pass easily through?
Flesh
96
# P4 - Radiation For Life What can X-rays not pass easily through?
Thicker and denser material like bone or metal.
97
# P4 - Radiation For Life What makes an X-ray image?
Varying amount of radiation that's absorbed (denser materials absorb more X-rays)
98
# P4 - Radiation For Life How is gamma used to treat cancer?
\*Gamma focused on tumour using wide beam. \*Beam rotated round patient - tumour at centre. \*Minimises exposure of normal cells to radiation, reducing risk of damage to rest of body.
99
# P4 - Radiation For Life What radiation can be used as medical tracers?
Radioactive isotopes that emit gamma (short half life - few hours)
100
# P4 - Radiation For Life How can a patient be given a medical tracer?
Injected, drunk, eaten or ingested.
101
# P4 - Radiation For Life How are medical tracers monitored?
Progress followed by radiation detector outside body.
102
# P4 - Radiation For Life What is an example of a medical tracer?
Iodine-123 absorbed by thyroid gland and shows if thyroid is taking all iodine it should.
103
# P4 - Radiation For Life Why must all isotopes in the body be beta or gamma?
Can penetrate tissue so are detectable outside. Can pass out easily.
104
# P4 - Radiation For Life How can medical instruments be sterilised?
Exposing them to high dose of gamma radiation.
105
# P4 - Radiation For Life Why does gamma radiation sterilise equipment?
It kills microbes
106
# P4 - Radiation For Life What is the advantage of using radiation instead of water to sterilise equipment?
Doesn't involve high temperatures. Plastic instruments can be sterilised without damaging them.
107
# P4 - Radiation For Life How can radiation be used as tracers in industry?
Tracks movement of waste material to find route underground of pipes or detect leaks/blockages
108
# P4 - Radiation For Life How is a leak detected using a radioactive tracer?
If detection of radioactivity stops/reduces must be a blockage/leak.
109
# P4 - Radiation For Life What must the isotope be for industrial tracers?
Gamma emitters so it can be detected through metal/pipe. Needs short half life.
110
# P4 - Radiation For Life Why does the industrial tracer need a short half life?
So it doesn't cause a hazard if it collects somewhere. Doesn't pollute water.
111
# P4 - Radiation For Life What source is used in a smoke detector?
A weak alpha source close to two electrodes.
112
# P4 - Radiation For Life How does a smoke alarm work?
In a fire, smoke particles are hit by alpha particles (less ionising of air) so current reduces, alarm sounds.
113
# P4 - Radiation For Life How does background radiation come from radioactivity of naturally occurring unstable isotopes?
All around us. In air, food, building materials and rocks. Large proportion of background radiation comes from natural sources.
114
# P4 - Radiation For Life How does background radiation come from space?
Known as cosmic rays. Come mostly from sun.
115
# P4 - Radiation For Life How does background radiation come from human activity?
E.g. Fallout from nuclear explosions, waste from industry and hospitals. Represents a small proportion of total.
116
# P4 - Radiation For Life How can the amount of background radiation vary?
Depending on where you are or job you have.
117
# P4 - Radiation For Life What 3 ways do we receive background radiation?
Naturally occurring unstable isotopes. Space. Human activity.
118
# P4 - Radiation For Life How can you work out the age of something using radioactive dating?
Measuring amount of radioactive isotope left in sample, and knowing its half life.
119
# P4 - Radiation For Life What fraction of the carbon in the air does carbon-14 make up?
1/10,000,000 (one ten-millionth)
120
# P4 - Radiation For Life What is the half life of carbon-14?
5730 years.
121
# P4 - Radiation For Life What happens when carbon-14 isotopes die?
Stop exchanging gas with air outside atmosphere and is trapped inside. Gradually decays.
122
# P4 - Radiation For Life How does uranium have a different half life?
Very long. Decay via series of short lived particles to produce stable isotopes of lead.
123
# P4 - Radiation For Life What is produced after 1 half life of uranium?
50% uranium 50% lead
124
# P4 - Radiation For Life What is produced after 2 half lives of uranium?
25% uranium 75% lead
125
# P4 - Radiation For Life What is the ratio of uranium to lead after 2 half lives?
1:3
126
# P4 - Radiation For Life What is the ratio of uranium to lead after 1 half life?
1:1
127
# P4 - Radiation For Life What is the ratio of uranium to lead before a half life?
1:0
128
# P4 - Radiation For Life What are nuclear power stations powered by?
Nuclear reactors
129
# P4 - Radiation For Life What happens in a nuclear reactor?
Controlled chain reaction takes place - nuclear fission.
130
# P4 - Radiation For Life What is nuclear fission?
Uranium/plutonium atoms split up - releasing energy as heat.
131
# P4 - Radiation For Life What happens after a nuclear reactor?
Heat from fission is used to produce steam. Steam turns turbines which drive generator, producing electricity.
132
# P4 - Radiation For Life What isotope is used in some nuclear reactors and bombs?
Uranium-235
133
# P4 - Radiation For Life What is uranium-235 like?
Quite stable
134
# P4 - Radiation For Life How do materials become radioactive?
When they absorb extra neutrons.
135
# P4 - Radiation For Life How is uranium-235 made radioactive?
By firing slow moving neutrons at the U-235 atom.
136
# P4 - Radiation For Life What does uranium-235 become to make it unstable?
Neutron joins, making it U-236 which is unstable.
137
# P4 - Radiation For Life What happens to the U-236?
Splits into 2 smaller nuclei, releasing energy and producing radioactive waste.
138
# P4 - Radiation For Life What does the split nucleus of U-236 also release?
2 or 3 fast moving neutrons which go on to produce a chain reaction.
139
# P4 - Radiation For Life What happens to neutrons from previous fission reactions of U-235?
They are used to hit other U-235 atoms
140
# P4 - Radiation For Life What is a nuclear bomb?
Chain reactions that are out of control.
141
# P4 - Radiation For Life How is the chain reaction controlled in nuclear reactors?
Using control rods
142
# P4 - Radiation For Life What are control rods usually made of?
Boron
143
# P4 - Radiation For Life What do control rods do?
Limit the rate of fission by absorbing excess neutrons.
144
# P4 - Radiation For Life What is nuclear fusion?
Two light nuclei combine to create a larger nucleus.
145
# P4 - Radiation For Life What is the equation for two hydrogen isotopes combining to form helium?
146
# P4 - Radiation For Life Where does all the energy released from stars come from?
Fusion at extremely high temperatures and pressures.
147
# P4 - Radiation For Life What is good about nuclear fusion?
Doesn't leave behind much radioactive waste and there is plenty of hydrogen available.
148
# P4 - Radiation For Life What is the big problem with nuclear fusion?
Only happens at really high pressures and temperatures (about 10,000,000 degrees C). No material can withstand that, so reactors are difficult to build. Safety issues.
149
# P4 - Radiation For Life Name an experimental fusion reactor...
JET (Joint European Torus)
150
# P4 - Radiation For Life Why are no fusion reactors producing electricity yet?
It takes more power to get up to temperature than reactor can produce.
151
# P4 - Radiation For Life Why is research into fusion being undertaken by international groups?
To share cost, expertise, experience and benefits (when problem solved)
152
# P4 - Radiation For Life What happens in a fusion bomb?
(AKA H-Bomb) Fission reaction creates high temperatures needed for fusion reaction which follows.
153
# P4 - Radiation For Life What does a new scientific theory have to go through before being accepted?
Validation Process
154
# P4 - Radiation For Life What is 'cold fusion'?
Nuclear fusion which occurs at room temperature.
155
# P4 - Radiation For Life Why is cold fusion not accepted?
Data was shared so experiments could be repeated. Very few managed to reproduce results reliably - not realistic method of energy production.
156
# P4 - Radiation for Life From duster to rod
Which direction do electrons move when a polythene rod is rubbed with a duster?
157
# P4 - Radiation for Life From rod to duster
Which direction do electrons move when an acetate rod is rubbed with a duster?
158
# P4 - Radiation for Life Electrons moving
What is a static charge caused by?
159
# P4 - Radiation for Life It can suddenly move which can cause sparks or shocks that may be dangerous.
What happens if enough static charge builds up?
160
# P4 - Radiation for Life By connecting it to earth with a metal strap (earthing).
How can a charged conductor be discharged safely?
161
# P4 - Radiation for Life Electrons flow down strap to ground if charge is negative and flow up strap from ground if positive.
How does earthing work?
162
# P4 - Radiation for Life Atoms or molecules with a charge
What are ions?
163
# P4 - Radiation for Life Dust particles are charged and attract opposite charge. Objects in home are insulators (get easily charged) and attract dust.
How does static attract dust?
164
# P4 - Radiation for Life When synthetic clothes dragged (head or other clothes) electrons scrape off, leaving static charge - two attract. Little sparks/shocks as charges rearrange themselves.
How does static affect clothing?
165
# P4 - Radiation for Life Walking on nylon carpet with insulating soles builds up charge. Touching metal door handle/water pipe allows charge to flow via conductor - little shock.
What causes shocks from door handles?
166
# P4 - Radiation for Life Charge may become large enough to make a spark - dangerous near inflammable gases or fuel fumes.
How can static on clothing become dangerous?
167
# P4 - Radiation for Life Fuel flowing out of pipe, paper drags on rollers or grain shoots out of pipe, static builds up. If too big, might spark - explosion in dusty/fumey places (petrol station).
When can static become dangerous (other than on clothes)?
168
# P4 - Radiation for Life Areas with inflammable liquids or a high concentration of oxygen (hospital operating theatre)
What kind of places is static dangerous in?
169
# P4 - Radiation for Life Make surface of a charged object conductive - provides an easy path for charges to move away.
How do anti-static sprays work?
170
# P4 - Radiation for Life Prevent static electricity moving through them - stops human getting shocked.
How do insulating mats and shoes work?
171
# P4 - Radiation for Life Spray gun charged and object given opposite to attract. Paint drops repel each other (fine spray).
How do paint sprayers work?
172
# P4 - Radiation for Life Method gives even coat and hardly any paint wasted. No shadows - everywhere covered.
What is the good thing about electrostatic paint sprayers?
173
# P4 - Radiation for Life Smoke particles reach chimney bottom, meet wire grid/rods with high voltage and (-) charge. Dust particles gain electrons (become (-)) Dust particles induce charge on earthed metal plates Dust attracted to metal plates - stick forming larger particles When heavy enough, particles fall off/knocked off with hammer Falls and is removed
How do dust precipitators work?
174
# P4 - Radiation for Life 2 paddles to power supply: Paddles firmly on chest (good electrical contact) and charged up Everyone moves away - operator holds insulated handles Charge passes through paddles to patient - heart contracts.
How does a defibrillator work?
175
# P4 - Radiation for Life more current will flow
If you increase the voltage....
176
# P4 - Radiation for Life less current will flow (or more voltage is needed to keep same current flowing)
If you increase the resistance...
177
# P4 - Radiation for Life As long as there is a complete loop - broke circuit means no current.
Current only flows when?
178
# P4 - Radiation for Life Carries voltage. Alternates between a high + and - voltage of about 230V
What does the live wire do?
179
# P4 - Radiation for Life Brown
What colour is the live wire?
180
# P4 - Radiation for Life Works together with fuse for safety
What does the earth wire do?
181
# P4 - Radiation for Life Completes tcircuit - electricity flows out through neutral - always at 0V.
What does the neutral wire do?
182
# P4 - Radiation for Life Blue
What colour is the neutral wire?
183
# P4 - Radiation for Life Green and yellow
What colour is the earth wire?
184
# P4 - Radiation for Life earthed
What must all appliances with metal cases be?
185
# P4 - Radiation for Life If appliance has casing that is non-conductive (e.g. plastic) - doesn't need earthing (never live)
What does double insulated mean?
186
# P4 - Radiation for Life A big current flows through live wire. Surge blows fuse and causes wire inside to melt. Cuts off live supply by breaking circuit.
What happens is a fault develops where the live wire touches the metal case?
187
# P4 - Radiation for Life Electric shocks by isolating appliance. Stops flex overheating which may cause fire. Prevent further damage to appliance.
When the fuse blows, what does this prevent?
188
# P4 - Radiation for Life Works like a fuse but can be reset and used again.
What is a circuit breaker?
189
# P4 - Radiation for Life As near as possible but just higher than normal operating current.
How should fuses be rated?
190
# P4 - Radiation for Life 3A, 5A and 13A
What are the fixed fuse ratings?
191
# P4 - Radiation for Life Rheostat - resistor whose resistance can be changed by turning a knob.
What is a variable resistor?
192
# P4 - Radiation for Life Alternating the current flowing through a circuit. Turn up resistance, current drops (vice versa).
What are variable resistors good for?
193
# P4 - Radiation for Life Electric charge has less space to move through.
Why do thinner wires increase resistance?
194
# P4 - Radiation for Life Steady - at a constant temperature
What is the resistance of a fixed resistor like?
195
# P4 - Radiation for Life Voltage / current
How is resistance calculated?
196
# P4 - Radiation for Life In series with other components
How is the ammeter set up in a circuit to measure resistance?
197
# P4 - Radiation for Life In parallel around component being tested.
How is the voltmeter placed in a circuit to measure resistance?
198
# P4 - Radiation for Life Potential difference
What is the official name for voltage around a test circuit?
199
# P4 - Radiation for Life Parts of a wave under high pressure (lots of particles)
What are compressions?
200
# P4 - Radiation for Life Parts under low pressure (fewer particles)
What are rarefactions in a wave?
201
# P4 - Radiation for Life A full cycle of a wave from crest to crest/compression to compression
What is wavelength?
202
# P4 - Radiation for Life How many complete waves there are per second passing a certain point. Measured in hertz. Sound - high frequency=high pitch
What is frequency?
203
# P4 - Radiation for Life Measured from rest position to crest. Tells you how much energy wave is carrying, or how loud it is.
What is amplitude?
204
# P4 - Radiation for Life Vibrations are along same direction as wave is travelling
How does a longitudinal wave move?
205
# P4 - Radiation for Life Vibrations are at 90 degrees to direction of travel of the wave
How does a transverse wave move?
206
# P4 - Radiation for Life Electric devices can be made which produce electrical oscillations of any frequency. Easily converted into mechanical vibrations to produce longitudinal waves beyond range of human hearing.
What is ultrasound?
207
# P4 - Radiation for Life Removing kidney stones. High energy of ultrasound at stone turns it into sand like particles. Particles pass out of body in urine. Doesn't need surgery and painless.
How does ultrasound work when breaking down accumulation in the body?
208
# P4 - Radiation for Life Waves pass through body but are reflected back when they meet a boundary between two different media. Echoes are processed by computer to produce video image.
How does ultrasound work in body scanning?
209
# P4 - Radiation for Life Ultrasound is great for imaging soft tissue. Safer doesn't damage cells.
What advantages does ultrasound have?
210
# P4 - Radiation for Life Better for viewing bone. Can damage living cells by being ionising radiation, causing cancer at high doses.
What do X-rays do compared to ultrasound?
211
# P4 - Radiation for Life Atoms with unstable nuclei that naturally decay at random
What are radioactive materials made up of?
212
# P4 - Radiation for Life Give out alpha, beta and gamma. Nucleus often changes into new element.
What happens as radioactive material decays?
213
# P4 - Radiation for Life Top number = number of protons and neutrons (AKA mass number)
What is the relative atomic mass number?
214
# P4 - Radiation for Life Number of protons
What is the atomic number?
215
# P4 - Radiation for Life Atoms of same element with different mass numbers
What is an isotope?
216
# P4 - Radiation for Life After alpha and beta, if nucleus has extra energy to get rid of. Emits gamma ray that has no mass or charge - atomic and mass number don't change.
When does gamma radiation happen in decay?
217
# P4 - Radiation for Life Helium nucleus of two protons and two neutrons
What is an alpha particle?
218
# P4 - Radiation for Life +2
What charge does an alpha particle have?
219
# P4 - Radiation for Life 4
What mass does an alpha particle have?
220
# P4 - Radiation for Life Decreases by 4 because it loses 2 protons and 2 neutrons
What happens to the mass number when a nucleus emits an alpha particle?
221
# P4 - Radiation for Life Decreases by 2 because it has 2 less protons
What happens to the atomic number when the nucleus emits an alpha particle?
222
# P4 - Radiation for Life Fast moving electron
What is a beta particle?
223
# P4 - Radiation for Life -1
What charge does a beta particle have?
224
# P4 - Radiation for Life 0
What mass does a beta particle have?
225
# P4 - Radiation for Life Doesn't change - lost a neutron but gained a proton
What happens to the mass number when a nucleus emits a beta particle?
226
# P4 - Radiation for Life Increases by 1 - has 1 more proton
What happens to the atomic number when a nucleus emits a beta particle?
227
# P4 - Radiation for Life Radioactivity of the source as whole decreases - older a resource, less radiation emitted.
What happens as more unstable nuclei decay?
228
# P4 - Radiation for Life Activity never reaches 0
What is the problem with trying to measure how quickly radioactive material decays?
229
# P4 - Radiation for Life Time taken for half of the radioactive nuclei now present to decay.
What is the definition of half life?
230
# P4 - Radiation for Life Activity falls quickly because lots of nuclei decay in a short time.
What does a short half life mean?
231
# P4 - Radiation for Life Activity falls slowly, because most of nuclei doesn't decay for a long time.
What does a long half life mean?
232
# P4 - Radiation for Life When some materials absorb ionising radiation - can enter living cells and interact with molecules.
What causes ionisation?
233
# P4 - Radiation for Life Charged particles called ions
What does ionisation produce?
234
# P4 - Radiation for Life Ionising radiation
What is nuclear radiation and X-rays types of?
235
# P4 - Radiation for Life Transfer energy to electrons. Electrons then have enough energy to escape from atom, ionising it and leaving it positively charged.
What can X-rays and gamma rays do to electrons?
236
# P4 - Radiation for Life Remove electrons from atom/molecule leaving them positively charged.
What can beta particles do to electrons?
237
# P4 - Radiation for Life Ionises it making it negatively charged.
What happens if a beta particle sticks to an atom?
238
# P4 - Radiation for Life Remove electrons, making atom positive.
What can alpha particles do to electrons in an atom?
239
# P4 - Radiation for Life 1. Relatively large - easy to collide with atoms or molecules 2. Highly charged - easily remove electrons from atoms they pass or collide with.
Why are alpha particles good ionisers?
240
# P4 - Radiation for Life Minor damage without killing cells. Can give rise to mutant cells which divide uncontrollably - cancer.
What do lower doses of ionising radiation tend to cause?
241
# P4 - Radiation for Life Kill cells completely, which causes radiation sickness if a lot of cells all get blasted at once.
What can high doses of ionising radiation tend to do?
242
# P4 - Radiation for Life Beta and gamma - can still get to delicate organs (pass through skin)
Which types of radiation are most dangerous outside the body?
243
# P4 - Radiation for Life It can't penetrate the skin
Why is alpha not dangerous outside the body?
244
# P4 - Radiation for Life Alpha - do all their damage in a localised area, highly ionising.
Which source of radiation is most dangerous inside the body?
245
# P4 - Radiation for Life Beta and gamma - less ionising, often pass straight out with very little damage
What sources of radiation are les dangerous inside the body?
246
# P4 - Radiation for Life High frequency
What level of frequency do X-rays and gamma rays have?
247
# P4 - Radiation for Life Short wavelength electromagnetic waves
What distance wavelength do X-rays and gamma rays have?
248
# P4 - Radiation for Life Released from some unstable atomic nuclei when they decay. No way to control when they are released.
How are gamma rays made?
249
# P4 - Radiation for Life By firing high speed electrons at a heavy metal like tungsten. Much easier to control production of than gamma.
How are X-rays produced?
250
# P4 - Radiation for Life Flesh
What can X-rays pass easily through?
251
# P4 - Radiation for Life Thicker and denser material like bone or metal.
What can X-rays not pass easily through?
252
# P4 - Radiation for Life Varying amount of radiation that's absorbed (denser materials absorb more X-rays)
What makes an X-ray image?
253
# P4 - Radiation for Life \*Gamma focused on tumour using wide beam. \*Beam rotated round patient - tumour at centre. \*Minimises exposure of normal cells to radiation, reducing risk of damage to rest of body.
How is gamma used to treat cancer?
254
# P4 - Radiation for Life Radioactive isotopes that emit gamma (short half life - few hours)
What radiation can be used as medical tracers?
255
# P4 - Radiation for Life Injected, drunk, eaten or ingested.
How can a patient be given a medical tracer?
256
# P4 - Radiation for Life Progress followed by radiation detector outside body.
How are medical tracers monitored?
257
# P4 - Radiation for Life Iodine-123 absorbed by thyroid gland and shows if thyroid is taking all iodine it should.
What is an example of a medical tracer?
258
# P4 - Radiation for Life Can penetrate tissue so are detectable outside. Can pass out easily.
Why must all isotopes in the body be beta or gamma?
259
# P4 - Radiation for Life Exposing them to high dose of gamma radiation.
How can medical instruments be sterilised?
260
# P4 - Radiation for Life It kills microbes
Why does gamma radiation sterilise equipment?
261
# P4 - Radiation for Life Doesn't involve high temperatures. Plastic instruments can be sterilised without damaging them.
What is the advantage of using radiation instead of water to sterilise equipment?
262
# P4 - Radiation for Life Tracks movement of waste material to find route underground of pipes or detect leaks/blockages
How can radiation be used as tracers in industry?
263
# P4 - Radiation for Life If detection of radioactivity stops/reduces must be a blockage/leak.
How is a leak detected using a radioactive tracer?
264
# P4 - Radiation for Life Gamma emitters so it can be detected through metal/pipe. Needs short half life.
What must the isotope be for industrial tracers?
265
# P4 - Radiation for Life So it doesn't cause a hazard if it collects somewhere. Doesn't pollute water.
Why does the industrial tracer need a short half life?
266
# P4 - Radiation for Life A weak alpha source close to two electrodes.
What source is used in a smoke detector?
267
# P4 - Radiation for Life In a fire, smoke particles are hit by alpha particles (less ionising of air) so current reduces, alarm sounds.
How does a smoke alarm work?
268
# P4 - Radiation for Life All around us. In air, food, building materials and rocks. Large proportion of background radiation comes from natural sources.
How does background radiation come from radioactivity of naturally occurring unstable isotopes?
269
# P4 - Radiation for Life Known as cosmic rays. Come mostly from sun.
How does background radiation come from space?
270
# P4 - Radiation for Life E.g. Fallout from nuclear explosions, waste from industry and hospitals. Represents a small proportion of total.
How does background radiation come from human activity?
271
# P4 - Radiation for Life Depending on where you are or job you have.
How can the amount of background radiation vary?
272
# P4 - Radiation for Life Naturally occurring unstable isotopes. Space. Human activity.
What 3 ways do we receive background radiation?
273
# P4 - Radiation for Life Measuring amount of radioactive isotope left in sample, and knowing its half life.
How can you work out the age of something using radioactive dating?
274
# P4 - Radiation for Life 1/10,000,000 (one ten-millionth)
What fraction of the carbon in the air does carbon-14 make up?
275
# P4 - Radiation for Life 5730 years.
What is the half life of carbon-14?
276
# P4 - Radiation for Life Stop exchanging gas with air outside atmosphere and is trapped inside. Gradually decays.
What happens when carbon-14 isotopes die?
277
# P4 - Radiation for Life Very long. Decay via series of short lived particles to produce stable isotopes of lead.
How does uranium have a different half life?
278
# P4 - Radiation for Life 50% uranium 50% lead
What is produced after 1 half life of uranium?
279
# P4 - Radiation for Life 25% uranium 75% lead
What is produced after 2 half lives of uranium?
280
# P4 - Radiation for Life 1:3
What is the ratio of uranium to lead after 2 half lives?
281
# P4 - Radiation for Life 1:1
What is the ratio of uranium to lead after 1 half life?
282
# P4 - Radiation for Life 1:0
What is the ratio of uranium to lead before a half life?
283
# P4 - Radiation for Life Nuclear reactors
What are nuclear power stations powered by?
284
# P4 - Radiation for Life Controlled chain reaction takes place - nuclear fission.
What happens in a nuclear reactor?
285
# P4 - Radiation for Life Uranium/plutonium atoms split up - releasing energy as heat.
What is nuclear fission?
286
# P4 - Radiation for Life Heat from fission is used to produce steam. Steam turns turbines which drive generator, producing electricity.
What happens after a nuclear reactor?
287
# P4 - Radiation for Life Uranium-235
What isotope is used in some nuclear reactors and bombs?
288
# P4 - Radiation for Life Quite stable
What is uranium-235 like?
289
# P4 - Radiation for Life When they absorb extra neutrons.
How do materials become radioactive?
290
# P4 - Radiation for Life By firing slow moving neutrons at the U-235 atom.
How is uranium-235 made radioactive?
291
# P4 - Radiation for Life Neutron joins, making it U-236 which is unstable.
What does uranium-235 become to make it unstable?
292
# P4 - Radiation for Life Splits into 2 smaller nuclei, releasing energy and producing radioactive waste.
What happens to the U-236?
293
# P4 - Radiation for Life 2 or 3 fast moving neutrons which go on to produce a chain reaction.
What does the split nucleus of U-236 also release?
294
# P4 - Radiation for Life They are used to hit other U-235 atoms
What happens to neutrons from previous fission reactions of U-235?
295
# P4 - Radiation for Life Chain reactions that are out of control.
What is a nuclear bomb?
296
# P4 - Radiation for Life Using control rods
How is the chain reaction controlled in nuclear reactors?
297
# P4 - Radiation for Life Boron
What are control rods usually made of?
298
# P4 - Radiation for Life Limit the rate of fission by absorbing excess neutrons.
What do control rods do?
299
# P4 - Radiation for Life Two light nuclei combine to create a larger nucleus.
What is nuclear fusion?
300
What is the equation for two hydrogen isotopes combining to form helium?
301
# P4 - Radiation for Life Fusion at extremely high temperatures and pressures.
Where does all the energy released from stars come from?
302
# P4 - Radiation for Life Doesn't leave behind much radioactive waste and there is plenty of hydrogen available.
What is good about nuclear fusion?
303
# P4 - Radiation for Life Only happens at really high pressures and temperatures (about 10,000,000 degrees C). No material can withstand that, so reactors are difficult to build. Safety issues.
What is the big problem with nuclear fusion?
304
# P4 - Radiation for Life JET (Joint European Torus)
Name an experimental fusion reactor...
305
# P4 - Radiation for Life It takes more power to get up to temperature than reactor can produce.
Why are no fusion reactors producing electricity yet?
306
# P4 - Radiation for Life To share cost, expertise, experience and benefits (when problem solved)
Why is research into fusion being undertaken by international groups?
307
# P4 - Radiation for Life (AKA H-Bomb) Fission reaction creates high temperatures needed for fusion reaction which follows.
What happens in a fusion bomb?
308
# P4 - Radiation for Life Validation Process
What does a new scientific theory have to go through before being accepted?
309
# P4 - Radiation for Life Nuclear fusion which occurs at room temperature.
What is 'cold fusion'?
310
# P4 - Radiation for Life Data was shared so experiments could be repeated. Very few managed to reproduce results reliably - not realistic method of energy production.
Why is cold fusion not accepted?