Activity

Discussion

Aim/Facts

This presentation follows the Making electricity presentation. The first activities reinforce some of the work done previously.

1. Show a Faraday torch or a wind-up torch.
Ask what is happening.
This is helpful to find out what the children know and also to establish basic ideas.
See apparatus list.

It is best to start with the torch uncharged so that the light does not switch on before the torch is shaken or wound as appropriate.
Ask the children what is needed to make the lamp light and then ask what is causing the electric current.

To demonstrate that energy can be used to generate an electric current which flows round a circuit to light a lamp.

2. Remind the children that energy is needed to push electrons along a wire to cause the electric current.
Slide 2

Point out that the energy from the person shaking the torch moves the strong magnet through the coil. This causes the electrons to move therefore an electric current to flow.

Revision of Electricity Generation Part 1

3. Michael Faraday invented the generator in 1831.
Slide 3

He invented the motor as well and is so famous that his picture is on some £20 notes.

4. Mains electricity is generated in power stations. The electricity is sent along wires to our homes, schools and factories. These generators are huge. Could ask children if they have seen the wires and pylons carrying the electricity to cities?
Slide 4

Ask for examples of devices which use mains electricity. Point out that a huge amount of electricity is needed for all the homes, factories and schools.

5. Huge amounts of energy are needed to turn the huge generators to produce sufficient electricity for our needs.
Slide 5

Discussion could revise uses of electricity in their homes and school.

6. Ask the children what is needed to make a generator.
Slide 6

Reinforce that a magnet moving near a wire causes an electric current to flow.

7. The energy is used to turn blades (a turbine) which then turn the generator. Explain that one way of turning the generator is to boil water and then use the steam to turn the turbine blades.
Slide 7

Note - a second click causes steam to turn the turbine.
Ask how we can boil water. They might suggest a kettle. Encourage them to think of camping fires and how they might boil very large amounts of water.
Another click starts the video of the kettle steam turbine.

8. Show the picture of the power station.
Slide 8

The coal is fed in and then is burned

• to boil water
• to make steam
• to turn the turbine blades
• to turn the generator
• to generate an electric current which is carried by wires held on pylons to where the energy is needed

Energy from burning coal or gas

9. Conventional power stations burn coal and some burn natural gas.
Slide 9

• burning coal pollutes the atmosphere
• burning gas causes less pollution
• both produce large amounts of greenhouse gases
• cooling towers waste energy
• the coal and gas on earth will run out

10. We can boil water using energy released from nuclear power stations. In these, nuclear reactors cause atoms to split and release energy.
Slide 10

This does not pollute the air but there are disadvantages because some of the waste is very dangerous and must be treated very carefully. It remains very dangerous for thousands of years.

Energy from splitting atoms

11. Explain that it is hot inside the Earth. It gets warm even at the depth of mines. Further down into the Earth it is very hot and at the centre it is about 7000⁰ C. In some countries the hot materials are close to the surface of the Earth and water can be pumped down to the hot rocks. This boils and can be used to turn the generators in a power station.
Slide 11 (and 12)

This source of energy will not run out because the Earth is huge and the amount of energy removed is relatively small.
A disadvantage is that it is only possible to use this source of energy in countries (such as Iceland) where there are hot rocks close to the Earth’s surface. (Generally where there are or have been volcanoes.)
It is not an option in the UK.

12. Explain that rotting vegetation and animal dung gives off heat because energy is being released. This can be used to heat water to heat homes or greenhouses.
Alternatively by chemical processes fuel can be produced from the vegetation. This can be burned to boil water to produce steam.
Slide 13

Energy from dung etc

13. All sources of energy so far have resulted in steam being produced to turn the turbines of a generator.
Generators can be turned by other sources of energy.

14. Show a toy water wheel used in a sandpit or bath. Point out that as the wheel turns it could be used to turn a tiny generator.
See apparatus list.
See safety notes.

Explain that running water can be used to turn huge turbines if there is a large stream of quickly flowing water.

15. A hydro electric power station is an enormous version of the toy. A lake situated high in the mountains is used. A dam is built so that water collects behind the dam. Some of the water is allowed to run down through pipes and is used to turn turbines which turn the generator.
Slide 14 and 15

Point out the pylons in the image hold the wires which carry the electricity to homes and factories.

Disadvantages:
These power stations have to be built in mountainous areas. Also there are problems if it doesn’t rain for a long time.

16. Water waves
The UK is surrounded by seas. There is huge potential for the energy carried by the waves to be used to generate electricity. However there are problems to be overcome by scientists before large scale generation is possible.
Slide 16

Ask the children whether they have been to the seaside. They will tell you about their visits.
Ask them to describe sea cliffs and point out that the water waves are so powerful that they wear the cliffs away. Ask them whether they have been in a boat on the sea. Point out that waves rock boats and make them move up and down. Therefore the waves can move generators.

17. Class activity.
See apparatus list.
The children can assemble the paper windmills, working in groups. The can blow them to show that they will turn.
Slide 17
See safety notes.

Discuss what the children find as they blow the windmills. The moving air causes the windmill to turn. They should try blowing in different directions and notice that the windmills may turn better when blown in certain directions. The children could take turns to hold their windmills in front of an electric fan. Switch this off to point out that if the wind stops blowing the windmill will not turn.

18. Wind turbines
Explain that windmills once used the wind to turn machinery to grind flour.
Modern windmills, known as wind turbines, turn when the wind blows. They are used to turn the generators.
Slide 18
Show a propeller on a string and use a fan to cause it to rotate.

Wind turbines do not pollute the air.
Once built, the energy is free.

Disadvantages:
They do not work if there is no wind.
Individual wind turbines produce small amounts of energy compared to power stations. Therefore large numbers are needed.
They can be unsightly in the countryside.
They make noises which disturb people living nearby.
They can be damaged by very strong winds.

19. Demonstration.
Slide 19
See apparatus list.
Using a solar panel show that when a light is shone on a solar panel then a buzzer can be made to sound. If the light is moved closer, then the buzzer will sound louder because more light is reaching the solar cell.
See safety notes.

The Sun gives out an enormous amount of energy which keeps us warm. The sunlight can be used to make electricity. This can be done by utilising very special materials (called semi-conductors).

Show slide 20 which has pictures of uses of solar cells in traffic signs, parking meters and even the face of a watch. The watch in the picture does not need a battery or need winding because the face is a solar cell.

Energy from sunlight

20. Extra Demonstration
Calculators powered by solar cells usually have a small battery which maintains the memory. If this is removed the calculator will not work unless light shines on the solar cell.
See apparatus list.
See safety notes.

This shows that solar cells need light to work.

21. Slide 21 shows the International space station which has huge panels of solar cells. They provide sufficient electricity to power all the needs of the astronauts and their experiments.

Encourage the children to ask questions. The framework holding the solar cells is 109 metres long. (The length of a football pitch or twice the length of an Olympic swimming pool!)
Point out that scientists have made such amazing developments possible.
Solar cells do not pollute the Earth but a lot of sunlight is needed.

22. Fusion
Explain that in the Sun atoms join together to form bigger atoms. This is called fusion. As this happens huge amounts of energy are given out. Scientists are carrying out experiments that have made this happen on Earth. It is very difficult because very high temperatures are needed to make it happen in very special conditions. It will take at least 20 years before it will be possible to generate very large amounts of energy this way.
Slide 22

Fusion takes place in hydrogen bombs.
But It is very difficult to generate electricity using fusion. It will take at least 20 years before it will be possible to generate large amounts of energy this way.
This does not pollute the air and the waste is less dangerous than from nuclear power stations used today.
When scientists have solved the problems we will have huge amounts of energy available as the raw materials come from sea water and there is lots of this.

Energy from small atoms joining together (like in the Sun)

23. Slide 23
Re-cap by asking the children what ways there are to generate electricity.

Ask them for the good points and the bad points. This could be a game with one side of the class providing the good points and the other providing the bad points.

Re-visit and summary

24. Slide 24
Point out that there are difficult choices to be made. That at present it seems that all of the ways of producing energy will be needed until fusion becomes a working possibility.

Point out that the problem will not be solved quickly and they, when they grow up, will be involved in big decisions.
If they learn more science they will be able to make wise, (informed) decisions and contribute to developing these new sources of electricity.

Lots of scientists are needed to solve the problems facing the whole World!

• Overview
• Apparatus List
• Safety Notes
• PowerPoint demonstration
• Download, Activities, Apparatus List and Safety Notes as a combined Word document for ease of printing