1. 9I Energy and electricity
Energy transfers
Energy in electricity
Power stations

2. 9I Energy and electricity
Energy transfers

3. To do anything, we need energy. The energy might...
9I Just do it!
To do anything, we need energy. The energy might...
heat something up
move something
make a noise
light something
Energy makes things happen. Can you think of three more examples where we can see its effects?

4. The energy that goes in is the input.
9I Energy changes
Devices that transfer energy are called transducers. An electric kettle is a transducer:
LATEST ENERGY NEWS
Energy cannot be created or destroyed – but it can be transferred.
electrical energy  heat energy
The energy that goes in is the input.
The energy that comes out is the output.
And it makes the tea!

5. What type of energy is stored in each object?
9I Energy stores
We need energy for anything we do. Some types of energy can be stored ready for use later.
What type of energy is stored in each object?
Object
Type of energy
electrical cells (batteries)
coiled spring in a clockwork alarm clock
petrol
a million tonnes of water held behind a dam
jam doughnut
chemical
potential (elastic)
chemical
potential (gravitational)
chemical

6. A transducer changes energy from one form to another.
9I Energy chains
A transducer changes energy from one form to another.
How does an iPod act as a tranducer?
Chemical energy in the battery is converted to electrical energy.
This is converted to sound energy by the headphones.
Write an energy chain to describe this process.
Remember:
Energy can be transferred along chains and change what it does.
There is the same amount at the end of the chain as at the beginning.
But it cannot be destroyed.

7. What is the output from each transducer?
9I Inputs and outputs
Which type of energy is the input for each transducer?
A electrical B sound C kinetic (moving air) D chemical (battery) E chemical (gas)
E chemical (gas)
A electrical
B sound
C kinetic (moving air)
D chemical (battery)
What is the output from each transducer?

8. 9I Write some energy chains
Can you write an energy chain for each transducer? Click the buttons to see the energy input and output.

9. Are you an energy expert? Give the word that matches each meaning.
9I Check out the words…
Are you an energy expert? Give the word that matches each meaning.
word
meaning
the ability to make something happen
the energy going into a transducer
the energy coming out of a transducer
a device that can change what energy does
the place where the energy goes to
the place where the energy comes from
energy
input
output
transducer
sink
source

10. 9I Energy and electricity
Energy in electricity

11. Electricity is useful because it transfers energy.
9I EIectricity and energy
Electricity is useful because it transfers energy.
What evidence can you see that electricity transfers energy?

12. What similarities are there between the model and the real car?
9I Meet a model
A model car is not the same as a real car. But it does tell you something about the real car that it was copied from.
What similarities are there between the model and the real car?

13. A model car shows you what the real car looks like.
9I Scientific models
A model car shows you what the real car looks like.
Scientists often use models to show you what things do, rather than what they look like.
For example, car designers might use a computer model to see how much petrol the engine uses at different speeds.
Stand by – here comes a model of an electrical circuit like the one below.

14. 9I Ski slope model for electricity

15. 9I Potential difference
The cell in a circuit provides a potential difference – a difference in energy between two points in the circuit.
The bigger the potential difference, the more energy can be transferred by the charge around the circuit.
Fill in the gaps!
ski slope model
electrical circuit
electrical  light energy in a bulb
charges
potential difference
cell
electrical energy
current
skiers
height difference
ski lift
gravitational potential energy
potential  kinetic energy down the slope
number of skiers per minute

16. Electrical energy costs money.
9I Costs of electrical energy
Electrical energy costs money.
If it’s generated in a fossil fuel power station, it also costs the environment. What sort of problems does it cause?

17. The more energy we can save, the less we have to generate.
9I Save it!
The more energy we can save, the less we have to generate.
Are these good ways to save energy?
Turn off the telly – it uses more electricity than anything else.
Only put enough water in the kettle for the tea you need. Boiling all the extra water is a waste of energy.
Dishwashers use so much energy. It’s better to do it by hand!
Sorry Mum, I can’t vacuum my room. I’m trying to save electricity!

18. Don’t forget, time must be in seconds!
9I Using electricity
When you boil a kettle or dry your hair, you do not ‘use up’ electricity. You use the energy that the electricity supplies.
energy (in joules) = power (in watts) x time (in seconds)
How much energy do these devices use?
Don’t forget, time must be in seconds!
15 W radio for 4 hours
30 W energy-efficient bulb for 6 hours
2 kW (2000 W) kettle for 5 minutes
100 W light bulb for 6 hours

19. Can you match each appliance to its correct power rating?
9I Do you have the power?
Can you match each appliance to its correct power rating?
150 W W W
light bulb
kettle
electric cooker
electric clock
one-bar electric fire
light bulb
kettle
electric clock
one-bar electric fire
electric cooker

20. 9I Energy and electricity
Power stations

21. Our electrical energy is generated in power stations.
9I Energy sources
Our electrical energy is generated in power stations.
To generate electricity we need a supply of energy – an energy source.
These devices all generate electricity. Where does their energy come from?
energy source:
gravitational potential energy from water stored high up
kinetic energy from the wheel turning
chemical energy in coal
light energy from the Sun
kinetic energy in moving air

22. What happens at a coal-fired power station?
9I What happens in a power station?
What happens at a coal-fired power station?
Click on the numbers to build up an energy chain.

23. 9I Wasted energy
The coal at a power station has stored chemical energy. But not all this energy leaves as electrical energy.
LATEST ENERGY NEWS
Energy cannot be created or destroyed – but it can be transferred.
Some energy is wasted along the way, as heat or sound energy. Does this mean the energy disappears?
The wasted energy does not disappear. It spreads out or dissipates through the surroundings. We cannot collect it and use it once it has been dissipated.

24. 9I Wasted energy
How much energy is wasted at each energy transfer in the power station?
kinetic energy  electrical energy 8%
chemical energy  heat and kinetic energy
45%
kinetic energy  kinetic energy
12%
boiler
generator
turbine 3%
electrical energy transferred
steam

25. Coal is burned to form steam, which turns the turbines.
9I Wasted energy
Coal is burned to form steam, which turns the turbines.
The steam is collected and sent to the cooling towers. Here it condenses to water again. This water will be heated to form steam again, and so on….
How much energy do you think is wasted here?