IOP Institute of Physics

# Experiments

Electricity Generation Part 2: Energy for the future

1. Show a Faraday torch or a wind-up torch.

Aim/Facts

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

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

Aim/Facts

 Activity Discussion 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.

3. Michael Faraday invented the generator in 1831.

 Activity Discussion 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

 Activity Discussion 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.

 Activity Discussion Slide 5 Discussion could revise uses of electricity in their homes and school.

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

 Activity Discussion 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.

 Activity Discussion 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.

Aim/Facts

• Energy from burning coal or gas
 Activity Discussion Slide 8 The coal is fed in and then is burned: To boil waterTo make steamTo turn the turbine bladesTo turn the generatorTo generate an electric current which is carried by wires held on pylons to where the energy is needed

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

 Activity Discussion Slide 9 There are problems: Burning coal pollutes the atmosphereBurning gas causes less pollutionBoth produce large amounts of greenhouse gasesCooling towers waste energyThe coal and gas on earth will run out

10. We can boil water using energy released from nuclear power stations.

Aim/Facts

• Energy from splitting atoms
 Activity Discussion 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.

11. Explain that it is hot inside the Earth.

Aim/Facts

• Energy from the Earth
 Activity Discussion 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.Slides 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.

Aim/Facts

• Energy from dung etc.
 Activity Discussion 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 As an introduction, ask the children whether they have ever put their hands inside a heap of grass mowings some hours after the grass was cut. The heap would have been hot inside.See apparatus listIf possible bring a large bag a warm grass mowings into the classroom and ask volunteers to place their hand inside.See safety notes

13. All sources of energy so far have resulted in steam being produced to turn the turbines of a generator.

 Activity Discussion Generators can be turned by other sources of energy.

14. Show a toy water wheel used in a sandpit or bath.

 Activity Discussion Point out that as the wheel turns it could be used to turn a tiny generator.See apparatus listSee 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.

 Activity Discussion 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.Slides 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

Aim/Facts

• Energy from water waves
 Activity Discussion 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

 Activity Discussion See apparatus listThe children can assemble the paper windmills, working in groups. The can blow them to show that they will turn.Slide 17See 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

 Activity Discussion 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 18Show 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 windIndividual wind turbines produce small amounts of energy compared to power stations. Therefore large numbers are neededThey can be unsightly in the countrysideThey make noises which disturb people living nearbyThey can be damaged by very strong winds

19. Demonstration

Aim/Facts

• Energy from sunlight
 Activity Discussion Slide 19See apparatus listUsing 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.

20. Extra Demonstration

 Activity Discussion 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 listSee 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.

 Activity Discussion 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

Aim/Facts

• Energy from small atoms joining together (like in the Sun).
 Activity Discussion 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.

23. Slide 23

Aim/Facts

• Re-visit and summary
 Activity Discussion 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.

24. Slide 24

Aim/Facts

• Lots of scientists are needed to solve the problems facing the whole World!
 Activity Discussion 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.