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Physics 21st Century > Sustainable :( Energy :( > Flashcards

Sustainable :( Energy :( Flashcards

1
Q

What is a primary energy source?

A

Fuel that is used in the form in which it is found.

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2
Q

Name some primary energy sources?

A

Fossil fuels; nuclear fuel; biofuels

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3
Q

What are secondary energy sources?

A

Energy that has been converted from a primary source, eg electricity

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4
Q

Where does most of our energy come from?

A

Burning fossil fuels

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5
Q

What is the burning of fossil fuels doing to the atmosphere?

A

Increasing the CO2

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6
Q

Why is it a problem that we are increasing the amount of CO2 in the atmosphere?

A

The greenhouse effect is causing global warming

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7
Q

What is likely to happen as the result of global warming?

A

Climate change; floods and storms

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8
Q

What is power?

A

The amount of energy transferred in one second

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9
Q

What is power measured in?

A

Watt

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10
Q

What is a watt?

A

1 joule in 1 second

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11
Q

What is the equation for energy transfer?

A

Energy transferred (J) = Power (W) x Time (s)

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12
Q

What is domestic electricity measured in?

A

KWh (Kilowatt -hours)

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13
Q

What is a kilowatt-hour?

A

The energy transferred by 1kW in an hour

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14
Q

What is the flow of electricity called?

A

Current

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15
Q

What is current measured in?

A

Ampère (Amp)

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16
Q

What is the voltage of a power supply measured in?

A

Volts

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17
Q

How can the rate of power transfer to an electrical device be measured?

A

Power (W) = current (A) x voltage (V)

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18
Q

What is the power of an electrical device?

A

The rate at which it transfers energy from the power supply. This is often called the rating.

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19
Q

What energy transfers occur when a current flows in a circuit?

A

Energy in the component transfers the energy into other useful forms; energy in the wires is converted into heat

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20
Q

How would you draw a diagram to show energy transfers?

A

Sankey diagram. The thickness of each arrow tail is proportional to the energy. Wasteful energy always flows down, useful energy to the right.

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21
Q

What is the efficiency of an electrical component?

A

Efficiency = energy usefully transferred/ total energy supplied

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22
Q

What can the values for efficiency be?

A

Between 1 and 0. Greater than 1 means you are creating energy.

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23
Q

How can you use less energy?

A

Use high efficiency A rated components; turning off components when they are not needed; not boiling more water than needed; cooking in the microwave.

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24
Q

What can the nation do to use less energy?

A

Use more efficient cars; live in houses with better insulation; building more efficient power stations.

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25
What will happen to global demand for energy?
It will rise due to population increases and increasing standard of living.
26
Which human activities have no impact on the environment?
They all do.
27
How can we reduce human impact on the environment?
recycling resources such as plastic, glass, paper; generating electricity from renewable sources of energy, eg water, wind, solar power.
28
What happens when you move a magnet near a circuit?
Current flows.
29
When does the flow of current induced by a magnet stop?
When the magnet stops moving.
30
How does a generator work?
A magnet is spun near a coil of wire.
31
How is the primary fuel in a power station used?
It boils water into steam, the steam pressure turns the turbines which spin the magnet.
32
How can turbines be turned directly?
Wind and water.
33
How does a spinning turbine make electricity?
It spins the shaft of the generator (and therefore the magnet)
34
How is the turbine set spinning?
By steam, hot exhaust gas, wind, water.
35
How do thermal power stations spin the turbine?
They burn the fuel to make steam. Some also use the hot exhaust gases to spin another turbine (mainly gas power stations do that).
36
How do hydro-electric power stations spin the turbine?
High pressure of water.
37
How do wind power stations spin the turbine?
They are using the convection currents in the air to spin the turbine, so solar energy
38
How do nuclear power stations spin the turbines?
They use the radioactive road to heat high pressure water which is cooling the fuel rods, which boils low pressure water, which produces steam, which spins the turbine.
39
What is the problem with the waste from nuclear power stations?
It is still radioactive, and therefore a health risk
40
What must be done with nuclear waste?
It has to be stored safely until it stops being dangerously radioactive.
41
What sort of radiation is emitted by nuclear waste?
Ionising radiation
42
What can ionising radiation do to body cells?
It can damage them
43
When an object is placed in the path of nuclear radiation it is
Irradiated
44
When an object has radioactive material mixed up with it it is
Contaminated
45
Why do we over-estimate the risks from ionising radiation?
We can't see it, or feel it; the effects can take a long time to develop; people worry about unfamiliar technology
46
Why is contamination much more serious than irradiation?
It can give a longer exposure to radiation; it is difficult to remove the radioactive material; it can be hard to stop the radioactive material from spreading.
47
What can statistics about death rates tell us?
They can be used to compare risks from different technologies; decide which technology needs to be controlled; decide which risks are too small to worry about.
48
How would you compare the risks of different technologies?
You take in to account the likelihood of an event, and the consequence of the event. The worse the consequences, the lower the acceptable likelihood.
49
What is an energy source that can be used over and over again?
Renewable
50
What are renewable sources of energy to spin turbines?
hydroelectric; wind; wave
51
Name advantages of hydroelectricity
They can provide large amounts of electricity; can respond to fluctuations in demand very quickly; can use excess power in the grid to pump water back up the hill
52
Name advantages of wind turbines
They are inexpensive to make, and cheap to maintain
53
Name disadvantages of hydroelectricity
They flood large areas of land; methane produced when plants rot in water; cost a lot to build
54
Name disadvantages of wind turbines
They need to be put in windy places; they can only generate electricity when it is windy enough; they kill birds.
55
Name advantages/disadvantages of wave power
Still experimental, not yet known
56
How can the environmental impact of renewable energy schemes be reduced?
By careful planning - wind turbines offshore; using hydroelectric dams to control rivers.
57
Why is electricity convenient?
It can transfer energy over long distances
58
What is the National Grid?
A network of cables that carries electricity over the whole of the UK
59
Why do power cables warm up?
Because they are wastefully transferring electric energy to thermal energy
60
How can you decrease the current while keeping the power constant?
Increase the voltage
61
How does the National Grid reduce wasteful energy transfers in the cables?
They use very high voltage.
62
How is the electricity changed for our homes?
Substations change the voltage to 230v
63
Where is the most energy wasted in the process of generating electricity and transferring it to homes?
In the power stations.
64
What is the efficiency of energy generation (including the national grid) in the UK?
.33
65
Which energy sources can generate large amounts of power?
Fossil fuels; nuclear power; hydroelectricity; biofuels.
66
Which energy sources for generating electricity rely on the right weather?
Wind; waves; solar
67
Energy sources that do not produce greenhouse gases?
Nuclear power; wind; waves; solar; geothermal
68
What is the environmental impact of using fossil fuels?
Greenhouse gases; extraction can be pollution risk; extraction can be dangerous
69
What is the environmental impact of using nuclear power?
Radioactive waste
70
What is the environmental impact of wind farms?
Noise, visual pollutions, concerns about possible bird deaths
71
What is the environmental impact of tidal and hydroelectric dams?
Flood large areas
72
Which energy sources will run out?
Fossil fuels; nuclear power
73
Which energy sources are free?
Wind; hydroelectric; tidal; solar; geothermal
74
What do you need to consider when choosing an energy source?
Environmental impact; cost of building and running the power stations; how much carbon dioxide and other waste it produces; reliability of the energy source; sustainability of the energy source; efficiency of transfer of energy
75
How is the output of a power station measured?
Millions of Watts - megawatts
76
What is the output of a power station using fossil fuels or radioactivity?
About 1000MW and it lasts about 40 years,
77
What power output do windfarms have?
About 300 MW, and lasts about 20 years.
78
What power output can hydroelectric power stations have?
About 10,000 MW, and last 80 years.
79
What have countries agreed to do in response to global warming?
Reduce their production of CO2
80
How will countries reduce the CO2 they produce?
Use less energy for heating, transport, electricity
81
How do vehicles, factories and power stations reduce their CO2 emissions?
Become more efficient.
82
Why is global demand for energy likely to rise?
Increasing population; increased standard of living
83
Why do people in industrialised countries have to use less energy?
We are the people who are using most of it
84
What have workplaces done to try to reduce CO2?
They are using cleaner, more efficient technology.
85
What is the implication of importing cheap goods?
They may have been made with polluting and inefficient technology
86
How can we secure our energy supply for the future?
Replace old power station with more efficient ones; use a mix of renewable energy sources; use more renewable energy sources as fossil fuels run out.
87
How much electricity do we need to be able to generate?
Enough to avoid power cuts caused by excess consumer demand.

Physics 21st Century (8 decks)

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