GCSE science A: physics electricity

P1.4 Methods we use to
generate electricity
AQA GCSE Science A

Various energy sources can be used to
generate the electricity we need. We must
carefully consider the advantages and
disadvantages of using each energy source
before deciding which energy source(s) it
would be best to use in any particular
situation.
Electricity is distributed via the National
Grid.

Candidates should use their skills, knowledge and
understanding to:

■ evaluate different methods of generating
electricity
■ evaluate ways of matching supply with
demand, either by increasing supply or decreasing
demand
■ compare the advantages and disadvantages of
overhead power lines and underground cables.

P1.4.1 Generating electricity

a) In some power stations an energy source is used
to heat water. The steam produced drives a turbine
that is coupled to an electrical generator.

Energy sources include:
■ the fossil fuels (coal, oil and gas) which are
burned to heat water or air
■ uranium and plutonium, when energy from
nuclear fission is used to heat water
■ biofuels that can be burned to heat water.


b) Water and wind can be used to drive
turbines directly.


c) Electricity can be produced directly from the
Sun’s radiation.

d) In some volcanic areas hot water and steam
rise to the surface. The steam can be tapped
and used to drive turbines. This is known as
geothermal energy.


e) Small-scale production of electricity may be
useful in some areas and for some uses, eg
hydroelectricity in remote areas and solar cells
for roadside signs.


f) Using different energy resources has
different effects on the environment. These
effects include:
• the release of substances into the atmosphere
• the production of waste materials noise and
• visual pollution the destruction of wildlife
habitats.

P1.4.2 The National Grid

a) Electricity is distributed from power stations
to consumers along the National Grid.

There are four main stages:
the fuel is burned to boil water to make steam
the steam makes a turbine spin
the spinning turbine turns a generator which produces electricity
the electricity goes to the transformers to produce the correct
voltage


b) For a given power, increasing the voltage
reduces the current required and this reduces the
energy losses in the cables.


c) The uses of step-up and step-down
transformers in the National Grid.

A transformer is an electrical device that changes
the voltage of an alternating current (ac)
supply, such as the mains electrical supply. A
transformer changes a high-voltage supply into a
low-voltage one, or vice versa.
A transformer that increases the voltage is called
a step-up transformer.
A transformer that decreases the voltage is called
a step-down transformer.

1. Why are coal, oil and natural gas non-
renewable resources?

A They contain carbon compounds.
B They cannot be replaced, except over
millions of years.
C Once used, they cannot be used again.

1. Why are coal, oil and natural gas non-
renewable resources?

A
B They cannot be replaced, except over
millions of years.
C

2. For a given amount of energy
released, which fuel releases the most
carbon dioxide?

A Coal
B Oil
C Natural gas

2. For a given amount of energy
released, which fuel releases the most
carbon dioxide?

A Coal
B
C

3. Which type of power station takes the
least time to start up?

A Gas-fired power station
B Nuclear power station
C Coal-fired power station

3. Which type of power station takes the
least time to start up?

A Gas-fired power station
B
C

4. What problem does sulfur dioxide cause?

A It contributes to global warming.
B It harms the ozone layer.
C It contributes to acid rain.

4. What problem does sulfur dioxide cause?

A
B
C It contributes to acid rain.

5. Why are uranium and plutonium used as
nuclear fuels?

A They are metals.
B They release a lot of heat when they burn.
C They are radioactive.

5. Why are uranium and plutonium used as
nuclear fuels?

A
B
C They are radioactive.

6. Which of the following is an advantage of
nuclear fuels?

A They are renewable energy resources.
B They do not emit harmful radiation.
C They do not produce greenhouse gases.

6. Which of the following is an advantage of
nuclear fuels?

A
B
C They do not produce greenhouse gases.

7. Which of the following is a disadvantage of
wind farms?

A They use a renewable energy resource.
B They are noisy and unsightly.
C They do not produce electricity at night.

wind farms?

A
B They are noisy and unsightly.
C

hydroelectric power produced by using a dam?

A The power station only works when the tide comes
in.
B River valleys and farmland are flooded by the dam.
C The power station only works on rainy days.

hydroelectric power produced by using a dam?

A
B River valleys and farmland are flooded by the dam.
C

9. Where does the heat energy for geothermal
energy resources come from?

A From radioactive decay in rocks
B From hot water and steam in the power station
C From the Sun warming the ground

9. Where does the heat energy for geothermal
energy resources come from?

A From radioactive decay in rocks
B
C

solar cells?

A They can supply electricity in remote areas.
B They do not produce electricity at night.
C They need complex moving parts.

solar cells?

A
B They do not produce electricity at night.
C

GCSE science A: physics electricity

Label and identify parts of the national
grid

Why are transformers an important part
of the national grid?

GCSE science A: physics electricity

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