I Energy and electricity Unit guide - Physicslocker...This unit builds on:work on electricity and...

I Unit guideEnergy and electricity

Sheet 1 of 1

© Harcourt Education Ltd 2004 Catalyst 3This worksheet may have been altered from the original on the CD-ROM.

Where this unit fits in Prior learningThis unit builds on: work on electricity and energy in unit 7I Energy resources, unit 7J Electrical circuitsand unit 8I Heating and cooling.

The concepts in this unit are: voltage (potential difference), energy conservation, energy dissipation and energy efficiency.

This unit leads onto:work on the reactivity of metals in unit 9F Patterns of reactivity and work on fuels in unit 9GEnvironmental chemistry. It relates to unit 9D Using control for electronic monitoring in the design andtechnology scheme of work, and to unit 18 Twentieth-century conflicts and unit 20 Twentieth-centurymedicine in the history scheme of work.

To make good progress, pupils startingthis unit need to:• know how to connect simple series and

parallel circuits• recall that fossil fuels and wind, waves

and the Sun are all energy resources• be familiar with the different ways in

which energy is transferred and stored.

Framework yearly teaching objectives – Energy• Recognise the idea of energy conservation as a useful scientific accounting system when energy is transferred; use this to explain energy transfers

in familiar situations, energy efficiency and energy dissipation.• Develop, from a simple model of energy transfer in electrical circuits, the idea of potential difference in electrical circuits.• Use the model of energy conservation to explain how:– the potential difference measured across cells or components shows how much energy is transferred from the cells to the current and from the

current to the components;– electrical energy can be generated using fuels, including the energy transfers involved; recognise possible environmental effects of this.

Expectations from the QCA Scheme of Work At the end of this unit …

… most pupils will … … some pupils will not have made somuch progress and will …

… some pupils will have progressedfurther and will …

in terms of scientific enquiry NC Programme of Study Sc1 2c, g, j, k, m, o

• identify patterns in measurements of voltage and usethese to draw conclusions about circuits

• identify and control key factors in investigating simplecells and identify patterns in their results, includingobservations that do not fit the main trends.

• measure the voltage of a range of cells• present data as charts or tables.

• relate energy transfer devices in thelaboratory to everyday appliances

• synthesise information from secondarysources about the development of theelectricity supply industry andcommunicate it clearly

• consider whether data is sufficient, andaccount for anomalies.

in terms of physical processes NC Programme of Study Sc4 1a, b, c, 5a, c, e, g

• describe some energy transfers and transformations infamiliar situations, including dissipated energy, andenergy transfer devices

• recognise that the voltage change across a circuitcomponent is a measure of its energy transfer

• describe how voltage originates from a chemical cell• give examples of the hazards of high-voltage circuits• compare the energy consumption of common electrical

appliances• describe how electricity is generated by energy from fuels,

and recognise possible environmental effects of this.

• describe some useful energy transferdevices

• recognise that any functioning circuitneeds a power supply to provide a voltageand that high voltages are hazardous

• recognise that electricity is a convenientway of ‘delivering’ energy, but that itmust be paid for and that its generationcan cause environmental problems

• give examples of how energy goes towaste.

• apply a model of voltage and energychanges to a circuit

• recognise that although the total energyin a system is conserved, energy can bedissipated

• use ‘power ratings’ in comparing thecosts of using different electricalappliances

• link the function of an electric generatorto magnetic effects.

Suggested lesson allocation (see individual lesson planning guides)Direct route

I1Make it work

I2Energy in and out

I3Using electricity

I4Power stations

MisconceptionsPupils often think that current is used up around a circuit. This is because they confuse current with energy.

Health and safety (see activity notes to inform risk assessment)Risk assessments are required for any hazardous activity. In this unit pupils use mains electrical equipment in their investigations. Pupils must notexperiment with mains electricity.

Booster 6Focus on energy – Making things happen

Extra lessons (not in Pupil book)

I2 Investigate: How to increase thevoltage in a fruit cell.

I4 Power stationsExtra lesson forActivity I4b.

Review and assess progress (distributedappropriately)

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I1Lesson planning

guideMake it work

Sheet 1 of 1© Harcourt Education Ltd 2004 Catalyst 3This worksheet may have been altered from the original on the CD-ROM.

Learning objectivesi Energy transfers in familiar contexts.ii Electricity is a useful means of transferring energy.iii Energy conservation and energy dissipation. (red only)

Scientific enquiryiv Use energy transfer diagrams to describe energy transfers.v Use a simple model to explain why dissipated energy is less useful. (red only)

Suggested alternative starter activities (5–10 minutes)

Introduce the unit

Unit map for Energy andelectricity.

Share learning objectives

• Describe some energytransfers and record them asdiagrams.

• Describe useful forms ofenergy, and what happens toit after the transfer.

• State that energy isconserved.

Problem solving

Pupils look at food labelsand decide which foodwould be best to eat a fewhours before a race.

Word game

Game of ‘rocket’ hangman torecap use of words kinetic,potential, chemical energy,heat (thermal), light, soundfrom Year 7.

Capture interest

Demonstration of usefulenergy transfers, e.g.spring-driven clock, eatingfoods, chemical change.

Suggested alternative main activitiesActivity

Textbook I1

Activity I1a Practical

Activity I1b Paper

Activity I1c Catalyst InteractivePresentations 3

Learningobjectivessee above

i, ii, iii and v

i, ii and iv

i, ii, iii and v

i

Description

Teacher-led explanation and questioning OR Pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.

Energy transfers Pupils observe processes and record the energytransfers taking place.

Wasted energy What happens to energy after it has been ‘used’?Activity to help pupils to realise that not all the energy ends upwhere we want it when energy is transferred.

Some examples of energy changes:• Sun, a plant growing (speeded up), being eaten, person running.• Power station, overhead lines, socket, using hair straightener.• Firework being assembled, moving up through sky, bursting with

loud sound and stars.

Approx.timing

20 min

20 min

15 min

10 min

Target group

C H E S

R/G G R S

✔

✔

✔

Suggested alternative plenary activities (5–10 minutes)

Review learning

Pupils look at alternatives toelectricity (e.g. candle instead oflight bulb) to remind themselvesof advantages of electricity.

Sharing responses

In pairs, pupils taketurns to go throughtheir answers toActivity I1a.

Group feedback

Challenge groups to write thelongest chain of energytransfers, including electrical,that they can think of.

Word game

Check progress using anacrostic about differenttypes of energy.

Looking ahead

Show pupils the symbol fora voltmeter and show themhow to add one to a circuit.

Learning outcomes

Most pupils will ...

• describe some energy transfers andtransformations in familiar situations

• recognise that electricity is a convenient wayof ‘delivering’ energy

• apply the idea that energy is conserved torealise that some of the energy is wasted

• describe that wasted energy is dissipated tothe surroundings.

Some pupils, making less progress will ...

• describe some useful energy transfer devices• recognise that electricity is a convenient way

of ‘delivering’ energy.

Some pupils, making more progress will ...

• also use the idea of energy conservation tocalculate the wasted energy that is dissipatedto the surroundings

• also use a simple model to explain whydissipated energy is less useful.

Key wordselectrical energy, conserved, energy conservation, red only: gravitationalpotential energy, dissipated

Out-of-lesson learningHomework I1Textbook I1 end-of-spread questionsActivity I1b

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I2Lesson planning

guideEnergy in and out


Learning objectivesi Know what voltage is and how to measure it.ii Realise that you see a voltage (potential difference) across a component if energy is put in or given out.iii Energy transferred in a circuit depends on voltage and current. (red only)

Scientific enquiryiv Use a model to explain how voltage relates to the energy transferred in a circuit, including resistance and dissipation. (red only)v Investigate how varying the number of cells in a series circuit affects the voltage across components and the energy transferred by the

component.vi Investigate how varying the number of components in a series circuit affects the voltage across each component.


Recap last lesson

Suggest an electricalappliance. Pupils writeenergy transfers onwhiteboard.

Share learningobjectives

• Describe what voltage is.• Describe how to use a

voltmeter.• Use a model to understand

energy transfers in acircuit. (Sc1)

Problem solving

Pupils recap electric circuitsand diagrams by wiring up aseries circuit and parallelcircuit, then answer somequestions.

Capture interest (1)

Pupils compare two trays ofequipment and identify thedifferences between mainsand battery equipment.


Discuss the effect of anelectricity power cut on acity. Consider school, home,hospital, transport.


Textbook I2


Activity I2b Practical

Activity I2cCatalyst InteractivePresentations 3


i, ii, iii and iv

i, ii and v

i, ii and vi

i and iv

Description


Investigating voltage: Batteries Pupils investigate the relationshipbetween the number of cells and the voltage across components in aseries circuit.

Investigating voltage: Components Pupils investigate therelationship between number of components and the voltage acrosscomponents in a series circuit.

Animation of ski lift model of electricity and voltage.

Approx.timing

20 min

30 min

30 min

10 min

Target group

C H E S

R/G G R S

✔

✔

✔ ✔ ✔


Review learning

Calculate voltage fordifferent combinations ofbatteries and components.

Sharing responses

Each group prepares asentence to say what theyfound out about voltage inActivity I2a or I2b.

Group feedback

Given circuit diagrams,pupils draw in thevoltmeter in the correctposition.

Word game

What am I? Pupilsdescribe a componentwhile other pupils guesswhat it is.

Looking ahead

Look at some batteries to seewhat they are made of. Show abattery demo: metal plates inacid producing a voltage. Leadsinto I2 Investigate.

Learning outcomes


• know how to measure voltage using avoltmeter

• recognise that the voltage change across acircuit component is a measure of its energytransfer

• describe how voltage originates from achemical cell.


• measure the voltage of a range of cells• know that you get a voltage change across

cells and across lamps because energy is put inby cells and given out by lamps

• recognise that any functioning circuit needs apower supply to provide a voltage.


• also consider whether data is sufficient, andaccount for anomalies

• also use a model to explain how energy istransferred in a circuit.

Key wordsvoltage, volts, voltmeter, red only: potential difference

Out-of-lesson learningHomework I2Textbook I2 end-of-spread questions

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I2Lesson planning

guideInvestigate: How to increase thevoltage in a fruit cell


Learning objectivesi Chemical energy can be transformed into electrical energy.

Scientific enquiryii Choose appropriate techniques and equipment.iii Identify and describe patterns in data.iv Draw conclusions.v Describe how to improve their work, e.g. by identifying strengths in the work of others.vi Explain results that do not fit a pattern that arises.


Setting the context

Look at a car battery ifavailable. Alternatively, usea potato clock.

Introduce the apparatus

Show the availableequipment: lemon, metalplates, etc.

Safety

Pupils consider what safetyprecautions are necessarywith equipment they will beusing.

Brainstorming (1)

In groups, pupils considerthe variables in theinvestigation.

Brainstorming (2)

In groups, pupils considerhow to keep all thevariables constant exceptthose they areinvestigating.

InvestigationActivity

Activity I2d Practical

Activity I2e Paper


i, ii, iii, iv, vand vi

i, iii and iv

Description

How to increase the voltage in a fruit cell Pupils plan and carryout an investigation to find out which two metals will produce thehighest voltage from a fruit or vegetable cell.

Voltage in a lemon battery Pupils plot a graph of results of anexperiment to find out if the voltage produced by a ‘lemon battery’depends on the size of the metal electrodes.

Approx.timing

50 min

15 min

Target group

C H E S

✔ ✔

✔


Review learning

Pupils use a list of possibleconclusions for Activity I2e anddiscuss whether the data supportsthem. Use the list to produce a final conclusion.

Group feedback

In groups, pupils discuss theirconclusions to Activity I2d.

Analysing

Look at results from differentgroups for Activity I2d. Discuss towhat extent the results wererepeated, and whether all resultscould be collected together (‘no’ ifvariables different).

Evaluating

Ask each group to give oneproblem that they encountered inActivity I2d and one improvementthey could make.

Learning outcomes


• identify and describe patterns in the voltageproduced by a fruit cell

• identify observations that do not fit trends.


• measure voltage in a fruit cell• present data as charts or tables.


• consider whether data is sufficient andaccount for anomalies.

Key wordscell, battery, voltmeter, volts, voltage

Out-of-lesson learningLook at batteries available in catalogues and shops (e.g. car batteries):Why are metal hydride rechargeable batteries better than nickel cadmiumrechargeables?Why do appliances with NiCd batteries have a bin crossed out on them?(and how should you dispose of them – does the local council tell you?)


I3Lesson planning

guideUsing electricity


Learning objectivesi Describe a range of high-voltage devices that are dangerous and the safety precautions used to avoid injury.ii Know that different electrical appliances consume different amounts of energy.iii Know that some electrical appliances are more energy efficient than others, because they dissipate less energy.

Scientific enquiryiv Investigate the energy consumption of a variety of electrical appliances.v Use a simple model to explain why dissipated energy is less useful.


Recap last lesson

Pupils read values onvoltmeters.

Share learningobjectives

• Describe how high voltagecan be dangerous.

• Recognise that someappliances use moreenergy than others.

• Recognise that someappliances are more energyefficient than others.

Problem solving

On whiteboards, all pupilsthink of a way of savingelectrical energy.


Show photos of dangers of high voltage.Catalyst InteractivePresentations 3


Show animations of devicesthat use energy at differentrates.Catalyst InteractivePresentations 3


Textbook I3


Activity I3b Paper


i, ii and iii

ii, iii and iv

ii, iii and v

Description


Using electricity Pupils measure the energy used by differentelectrical appliances.

Using Sankey diagrams Pupils use Sankey diagrams to show howmuch energy is transferred, conserved and dissipated

Approx.timing

20 min

30 min

20 min

Target group

C H E S

R/G G R S

✔

✔


Review learning

Build up a table ofelectrical appliances on theboard (high energy user, orsmall energy user, and is itefficient?).

Sharing responses

Pupils work in groups toorder a list of appliancesand running times fromhigh energy to low energy.

Group feedback

Discuss results forelectrical appliances fromActivity I3a.

Word game

Pupils play a game ofhangman with wordslike efficiency,conserved, dissipated.

Looking ahead

Pupils think about whereelectrical energy for the homecomes from. How many differenttypes of power station/generatorcan they remember from Year 7?

Learning outcomes


• give examples of the hazards of high-voltagecircuits

• compare the energy consumption of commonelectrical appliances

• know that energy must be paid for• relate energy efficiency to wasted energy

dissipated to the surroundings.


• give examples of hazards of common high-voltage circuits

• know that different electrical appliances havedifferent energy consumptions

• know that energy must be paid for• give examples of how energy goes to waste.


• also use Sankey diagrams to represent energytransfers and energy efficiency in aquantitative manner.

Key wordsenergy efficiency, dissipate, red only: power rating, Sankey diagram

Out-of-lesson learningHomework I3Textbook I3 end-of-spread questionsActivity I3b


I4Lesson planning

guidePower stations


Learning objectivesi How power stations generate electricity.ii Describe the energy transfers that happen in a power station.iii Discuss the environmental impact of power stations that burn fossil fuels.

Scientific enquiryiv Use secondary sources to investigate the environmental impact of power stations.


Recap last lesson

True/false quiz aboutelectricity consumption.


• Describe how power stationswork.

• Identify the energy transfersin a power station.

• Use secondary sources toinvestigate the effect ofpower stations on theenvironment. (Sc1)

Problem solving

Plan what to do for a daywhen electricity is rationedand only available atcertain times.

Brainstorming

Recap knowledge from Years7 and 8 on what fossil fuelsare and where they comefrom.

Capture interest

Show photos of powerstations highlightingimportant features.Catalyst InteractivePresentations 3


Textbook I4


Activity I4b Discussion


i, ii and iii

i and ii

i, iii and iv

Description


Inside a power station Pupils observe two demonstrations and relatethem to the energy transfers that happen in a power station burningfossil fuels.

Comparing power stations Research about the environmental impactof different types of power station. Groups choose one method ofgenerating electricity and share results. Pupils select the best powerstation for different environments.

Approx.timing

20 min

25 min

50 min

Target group

C H E S

R/G G R S

✔ ✔ ✔

✔


Review learning

Show a model steam engineand talk about the differentparts in relation to a powerstation.

Sharing responses

Pupils order cards to recappower station and energychanges, as used in Activity I4a.

Group feedback

Pupils sort comments aboutpower stations into ‘for’,‘against’ and ‘neutral’.

Word game

Loop game on whole unit tocheck progress.

Looking back

Pupils revise andconsolidate knowledge fromthe unit.

Learning outcomes


• describe how electricity is generated byenergy from fuels, and recognise possibleenvironmental effects of this

• realise that power stations are not totallyenergy efficient, but some are more energyefficient than others

• realise that some power stations have moreenvironmental impact than others.


• recognise that electricity generation cancause environmental problems.


• also link the function of an electric generatorto magnetic effects

• also synthesise information from secondarysources about the development of theelectricity supply industry and communicate itclearly.

Key wordsgenerator, turbine

Out-of-lesson learningHomework I4Textbook I4 end-of-spread questions


I Unit mapEnergy and electricity


Copy the unit map and use these words to help you complete it.You may add words of your own too.

acid rainbatterychemicalcoalconductivityconservationcurrentefficiencyelectricalenergy dissipatedenergy wastedgasgeneratorsglobal warming

gravitationalhigh voltagehydroelectricjouleskineticlightnon-renewableoilpotentialpotential difference Rpower ratingpower stationsrenewableresistance

Sankey diagrams Rsaving energysolar powersoundstrainthermalturbinesvoltagevoltmetervoltswattswaveswind

Energy andelectricity

About energy –types andtransfers

Electricitygeneration

Energy – consumer issues(cost, waste and safety)

Electric circuits and voltage

Unitmaps.qxd 18-Jun-04 11:36 AM Page 9


I1 StartersMake it work

Introduce the unit� Either draw the outline of the unit map on the board

then ask pupils to give you words to add, saying where toadd them. Suggest some words yourself when necessaryto keep pupils on the right track.

� Or give out the unit map and ask pupils to work ingroups deciding how to add the listed words to thediagram. Then go through it on the board as each groupgives suggestions.

Share learning objectives� Write the learning objectives on the board and show why

it is important that we know about these ideas.

� Energy makes things happen. All the things we want todo, whether for fun or for life saving and everything inbetween, need a source of energy. If we understandenergy changes we can make better use of energy.

Problem solving� Pupils work in groups looking at food labels. They decide

which would be best to eat a few hours before a race.

� Pupils compare food values taken from chocolate sweets,breakfast cereal, pasta, and a banana.

� Remind pupils that we get energy from food, and needenergy for movement. It is measured in J, or kJ, and somefoods have more than others. (The issue of sugar versuscarbohydrate and amount of saturated fat may be knownby some and may lead to interesting discussion.)

Word game� Play a game similar to hangman but an ‘astronaut’ is

launched into space instead.

� Use five lines to draw a rocket, making it large enough to draw a matchstick man of head and five lines inside (11 false letters leads to launch of the rocket).

➔ Unit map

➔ Pupil sheet

Equipmentone calculator per group

AnswersChocolate: too much fat and sugar.Cereal and milk: probably not enoughenergy.Pasta/bananas: some runners do eat pasta,some recommend bananas. The aim is asteady release of energy, so need highcarbohydrates in form of starch and nottoo much sugar. Banana is very low inprotein and fat and is easily digested.

Wordskinetic, potential, chemical, energy, electrical, heat, thermal, light, sound


Introduce the unit

Unit map for Energyand electricity.


• Describe some energy transfers andrecord them as diagrams.

• Describe useful forms of energy, andwhat happens to it after the transfer.

• State that energy is conserved.

Problem solving

Pupils look at foodlabels and decidewhich food would bebest to eat a few hoursbefore a race.

Word game

Game of ‘rocket’ hangman torecap use of words kinetic,potential, chemical energy,heat (thermal), light, soundfrom Year 7.

Capture interest

Demonstration of usefulenergy transfers, e.g.spring-driven clock, eatingfoods, chemical change.

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I1 StartersMake it work (continued)

Capture interest� Pupils watch demonstrations of useful energy transfers

(spring-driven clock, eating foods, chemical change).

� Pupils answer the following questions for eachdemonstration.

1 What is the energy source/input?2 Is the energy stored?3 What is the useful energy output?4 Is energy wasted? (Yes)5 What energy transfers are not useful?

Equipmentwind-up alarm clock; food (could be a largebreakfast cereal box); Bunsen burner (lit);magnesium ribbon and tongs

AnswersWind-up clock1 Kinetic (winding spring); 2 Yes, as elasticin spring; 3 Kinetic (clock hands); 5 Sound(ticking) and heat.

Eating food1 Light from Sun to make food originally,then chemical; 2 Yes, as chemical after weeat it until we need it; 3 Our energy, kineticand reactions in cells and the body; 5 It endsup as heat (but we need to keep warm, so isit all really wasted? – discussion point).

Burning magnesium ribbon(not strictly useful, but used in flares andfireworks – and we can’t let off a flare in the laboratory) 1 Chemical; 2 Yes, chemical;3 Light; 5 Heat.

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I1 StartersMake it work

Problem solving

Which of these foods would be the best choice to eat2 hours before running or swimming in a race?

100 g of M&M’s chocolate sweets(almost two 55 g bags)


Nutrition information Per 100 gramsenergy kJ 2050protein g 4.7carbohydrate g 71.4 of which sugars g 64.9fat g 20.9

Nutrition information Per 100 gramsenergy kJ 431protein g 15.7carbohydrate g 17of which sugars g 4.9fat g 1.76

Nutrition information Per 100 gramsenergy kJ 1529protein g 11.9carbohydrate g 74.2 of which sugars g 4.7fat g 1.7

Nutrition information Per 100 gramsenergy kJ 415protein g 1.03carbohydrate g 23.43 of which sugars g 20.9*fat g 0.48

*For a yellow banana. (The amount of sugar starts low when the banana is green andincreases as more starch turns to sugar during ripening.)

Weetabix and semi-skimmed milk – 100 g(one Weetabix and about 80 ml of milk)

100 g of pasta

One medium banana (about 100 g)



I2 StartersEnergy in and out

Recap last lesson� Pupils suggest a use of an electrical appliance.� Pupils write down the energy transfers involved, or pupils could write

the energy at start, at the end and then fill in intermediate steps.

Share learning objectives� Write the learning objectives on the board and show why it is

important that we know about these ideas.� Ask pupils what items they have which need batteries and how they

know which one to buy when a replacement is needed.� This establishes that voltage is important, and batteries have different

voltage.� How do they know when batteries are flat? Apart from not working,

voltage drops. So it can be useful to be able to measure voltage.� To understand voltage in circuits it is useful to have a model, so that

we can predict what will happen in different situations, e.g. addingmore bulbs to a circuit.

Problem solving� Pupils work in pairs or groups to wire up the series circuit and the

parallel circuit shown on the pupil sheet.� Pupils answer the question about the current in parallel circuits.

Capture interest (1)� Pupils look at two trays of equipment. One tray has mains electrical

components and the other has battery equipment.� Ask pupils to suggest differences, and why. These can be verbal

suggestions or a written list.� Finish with a warning not to use battery equipment with mains voltages.

Capture interest (2)� Explain to pupils that for all cities and areas of the country, emergency

plans are ready so that police, armed forces, emergency services, etc.,know what to do if a particular disaster occurs.

� Suppose that a disaster cuts off power to the school and all thesurrounding area spreading as far as all the pupils’ homes. There wouldbe no power for 2 weeks.

� The first step to producing a plan is to list the problems this wouldcause. Explain that they are going to do this.

� Divide pupils into groups. Each group considers one of: transport,hospitals and care of sick and disabled, schools, homes, businesses,shops, farms. (Alter groups as appropriate to your area.)

� Each group to provide a short list of the biggest problems.� Ask for each group to report to the class the two biggest problems the

power cut would cause.

➔ Problem solving pupil sheet

Problem solving equipmenta tray for each group of twocells in holders; switch;ammeter; two lamps and six connecting wires

Problem solving answers1 Depends on components;2 About twice the answer toQuestion 1; 3 Current splitsup and some goes each way(splits equally only if lampsare identical).

Capture interest (1) equipmentTray 1: a 13 A mains plug;light switch; socket; fusesand connecting cables(three-core cable); maybe anitem with a warning aboutgetting a qualifiedelectrician

Tray 2: batteries in holders;lamps; connecting leads;different types of connectorand crocodile clips; switches, etc.

Capture interest (1) answersMains components are wellinsulated and designed sothat you can’t touch themetal parts even accidentally.Plug includes a fuse, and anearth wire. Mains voltage cankill. Batteries are safe.


Recap last lesson

Suggest an electricalappliance. Pupilswrite energy transferson whiteboard.


• Describe what voltage is.• Describe how to use a voltmeter.• Use a model to understand energy

transfers in a circuit. (Sc1)

Problem solving

Pupils recap electric circuits anddiagrams by wiring up a seriescircuit and parallel circuit, thenanswer some questions.


Pupils compare two trays ofequipment and identify thedifferences between mainsand battery equipment.


Discuss the effect of anelectricity power cut on a city. Consider school,home, hospital, transport.


Sheet 1 of 1

StartersI2 Energy in and out


I2 StartersEnergy in and out

Problem solving

1 Connect up this series circuit: 2 Connect up this parallel circuit:

What is the current throughthe ammeter?


3 What happens to the current at the point marked P on the circuit?

A

P

A

Problem solving

1 Connect up this series circuit: 2 Connect up this parallel circuit:



3 What happens to the current at the point marked P on the circuit?

A

P

A




I2 StartersInvestigate: How to increase thevoltage in a fruit cell

Setting the context� Show pupils a lead acid car battery. Show the lead plates

inside. Show the liquid and test it with universalindicator paper to show that it is a strong acid. If it ischarged, measure the voltage.

� Alternatively, show pupils a ‘potato’ or ‘fruit cell’ clock.Measure the voltage between the contacts.

Introduce the apparatus� Show pupils a tray of the available equipment which can

be used for the investigation. Go through all the itemswith them.

Safety� Ask pupils to work in pairs to list the hazards involved in

this investigation.

� Pupils then decide how to minimise the danger presentedby each hazard.

� Pairs report back to a class discussion during which afinal set of safety procedures is listed on the board.

Brainstorming (1)� Ask pupils to discuss in groups what the variables are in

the investigation.

� Ask them to decide what variable should be changed(independent variable) and what should be measuredduring the investigation (dependent variable).

� Ask individual pupils for their ideas. Use a classdiscussion to finalise the details of the two variables.

Brainstorming (2)� Ask pupils to work in groups to consider the questions

opposite.

� Use answers from individual pupils to initiate classdiscussion about fair testing and reliability of results.

Equipmentlead acid car battery; universal indicatorpaper; voltmeter; potato or fruit cell clock;voltmeter

Note: Lead acid car batteries are extremelyhazardous if short circuited. They are alsovery heavy and contain quite concentratedsulphuric acid. Do not allow pupils toaccess these batteries.

Equipmentone set of the equipment for Activity I2d(see Technician sheet for I2d)

Questions1 What needs to be done to make this

a fair test?

2 Will the experiments need to berepeated? Why?

3 Will a preliminary investigation beneeded? Why?


Setting the context

Look at a car battery ifavailable. Alternatively, usea potato clock.

Introduce the apparatus

Show the availableequipment: lemon, metalplates, etc.

Safety

Pupils consider what safetyprecautions are necessarywith equipment they will beusing.

Brainstorming (1)

In groups, pupils considerthe variables in theinvestigation.

Brainstorming (2)

In groups, pupils considerhow to keep all thevariables constant exceptthose they areinvestigating.



I3 StartersUsing electricity

Recap last lesson� Pupils read the values on voltmeters shown on the pupil

sheet.

Share learning objectives� Write the learning objectives on the board and show

why it is important that we know about these ideas.

� High voltages are dangerous. We need to understandwhy and how to avoid danger to ourselves and others.

� If we understand that some appliances use more energy,we understand when higher current and voltage is used,why it costs more, and why it is more dangerous.

� Some appliances are more efficient – this can save usmoney and is better for the environment.

Problem solving� Pupils think of a way of saving electrical energy. Ask

each pupil to write an idea on individual whiteboards.

� Discuss which ideas are practical.

Capture interest (1)� Look at photos of dangers of high voltage and discuss

what precautions to take to stay safe.

Capture interest (2)� Pupils watch animations of use of electricity. Discuss

how the amounts are very different and depend on thetime as well as the appliance.

� This is shown by a train, kettle and light bulb connectedto digital joulemeters. Totals are also given for typicaltimes of use.

� Compare totals for 1 hour journey = 1.152 × 1010 J (write out with all zeros), boiling kettle, e.g. 3 minutes = 540 000 J, and light on for 6 hours in evening = 1 296 000 J.

➔ Pupil sheet

AnswersA 1.5 V; B 0.73 V; C 1.1 V; D 3.6 V; E 2.9 V;F 4.0 V; G 8.5 V

➔ Catalyst Interactive Presentations 3



Recap last lesson

Pupils read values onvoltmeters.


• Describe how high voltage can bedangerous.

• Recognise that some appliances usemore energy than others.

• Recognise that some appliances aremore energy efficient than others.

Problem solving

On whiteboards, all pupilsthink of a way of savingelectrical energy.


Show photos of dangersof high voltage.Catalyst InteractivePresentations 3


Show animations of devicesthat use energy at differentrates. Catalyst InteractivePresentations 3


I3 StartersUsing electricity

Recap last lesson

What is the voltage in volts shown on each voltmeter?


v +– v +–

A B

01

2 3 45

6v

01

2 3 45

6v

C D

01

2 3 45

6v v

0

5 10

15

0

5 10

15

E F

G

v



I4 StartersPower stations

Recap last lesson� Pupils consider statements read by the teacher (or a

selected pupil). For each one they write ‘true’ or ‘false’ ona whiteboard, then the whole class shows their answers.Discuss the answers.

Share learning objectives� Write the learning objectives on the board and show why

it is important that we know about these ideas.

� We are very dependent on electricity. We use it a lot, andsometimes would not survive without it. We should notjust trust power companies and the government to makesure it will always be available – sometimes they makethe wrong decisions, or decisions based on profits.

� This means we need to know how they work, how efficient they are (so what energy transfers there are)and the effect on the environment.

Problem solving� Ask pupils to imagine this situation: the Prime Minister

announces that the government has miscalculated andfossil fuels will run out soon, so from next year electricitywill be rationed. You can only have it from 6 am to 8 am,10 am to 11 am, 4 pm to 6 pm and 9 pm to 10 pm. Howwould this affect their day?

� Some groups could plan how to spend a weekday andsome a Saturday.

Brainstorming� Working in groups pupils consider these questions: What

are fossil fuels? Where do they come from? Why do weuse them? Ask pupils to give advantages anddisadvantages.

Capture interest� Pupils look at photos of power stations. Ask if they can

point out the main features on each photo.

➔ Pupil sheet

Answers1 False; 2 True; 3 True; 4 False; 5 False; 6 False; 7 True; 8 True



Recap last lesson

True/false quiz aboutelectricity consumption.


• Describe how power stations work.• Identify the energy transfers in a

power station.• Use secondary sources to

investigate the effect of powerstations on the environment. (Sc1)

Problem solving

Plan what to do for aday when electricity isrationed and onlyavailable at certaintimes.

Brainstorming

Recap knowledge fromYears 7 and 8 on whatfossil fuels are and wherethey come from.

Capture interest

Show photos of power stationshighlighting importantfeatures. Catalyst InteractivePresentations 3


I4 StartersPower stations

Recap last lesson

True or false?

1 An electric light bulb uses more energy in an hour than anelectric kettle because it gives out light.

2 In one hour a dishwasher uses more electricity than a fridgebecause it heats the water.

3 Electric light bulbs waste most of the energy put in becausethey produce so much heat.

4 A microwave oven uses more electricity than a conventionalelectric cooker.

5 The electricity meter records the current in amps that is used.6 In one hour a television uses more electrical energy than a

washing machine.7 Electric lights use a lot more energy than you expect because

they are on for so many hours.8 A lot of energy would be saved if people didn’t leave their

televisions on standby.



I1aTeacher

activity notesEnergy transfers

Running the activityThis is a circus of five short activities. Pupils, in pairs, move from activity to activity. Ideally there should befour sets of apparatus:� a kettle of water to boil and allow to cool� a whistle (with disinfectant)� a circuit with a battery, lamp and switch� a ball to lift up and drop� a clockwork toy to wind and run down

Core: Pupils have to think about the energy transfers involved, and about how useful energy is at the end ofthe process. The questions encourage more able pupils to think about energy dissipation.

Other relevant materialSkill sheet 16: Energy transfer diagrams

Expected outcomesPupils think about where the energy originally came from (e.g. the Sun) and where it finally ends up(usually dissipated across many air particles). They may have difficulty isolating one step in the process torepresent with an energy transfer diagram.

PitfallsThe discussion is more important than representing the energy transfer as a diagram.

Safety notesThe whistle should be disinfected after each use.

Pupils should be warned not to touch the kettle when hot.

Scalds from steam are particularly unpleasant. Use running cold water for several minutes on anyone whogets scalded.

AnswersKettle cooling

1 Electricity (power station/fossil fuel/wind/waves/Sun).

2 In the air (as thermal energy).

3

4 Energy is less useful as it is spread out between many air particles.


Type Purpose DifferentiationPractical Pupils revise energy transfers and are introduced to energy conservation. Core

energy stored asthermal energy

in water

energytransferred as

electrical energy

energy stored asthermal energy

in air


kinetic energy


kinetic energy

I-Teachers.qxd 08-Jun-04 2:04 PM Page 1

Blowing whistle

1 Pupil’s energy (kinetic of muscles/chemical in food/light from Sun).

2 In the air as thermal energy.

3

4 Energy is less useful as it is spread out between many particles.

Lighting lamp

1 Chemical energy stored in battery.

2 In the air as thermal energy.

3


Lifting and dropping ball


2 In the air, the ball and the ground as thermal energy.

3


Winding up clockwork toy


2 In the air and the toy as thermal energy.

3


I1aTeacher

activity notesEnergy transfers (continued)

Sheet 2 of 2


energy transferred as

kinetic energy


sound energy


thermal and light energy

energy stored aschemical energy

in battery


electrical energy


kinetic energy

energy stored asgravitational (potential)

energy in ball


kinetic energy


kinetic energy

energy stored as strain energy

(potential) in spring


kinetic energy


sound energy


I1aTechnician

activity notesEnergy transfers

EquipmentFour sets of:

� a kettle of water, recently boiled� a whistle and disinfectant� a circuit to light a lamp� a ball� a clockwork toy


For your informationRunning the activityThis is a circus of five short activities. Pupils, in pairs, move from activity toactivity. Ideally there should be four sets of apparatus:

� a kettle of water to boil and allow to cool� a whistle (with disinfectant)� a circuit with a battery, lamp and switch� a ball to lift up and drop� a clockwork toy to wind and run down

Core: Pupils have to think about the energy transfers involved, and about howuseful energy is at the end of the process. The questions encourage more ablepupils to think about energy dissipation.

Expected outcomesPupils may think about where the energy originally came from (e.g. the Sun)and where it finally ends up (usually dissipated across many air particles). Theymay have difficulty isolating one step in the process to represent with anenergy transfer diagram.

PitfallsThe discussion is more important than representing the energy transfer as adiagram.

Safety notesThe whistle should be disinfected after each use.

Pupils should be warned not to touch the kettle when hot.

Scalds from steam are particularly unpleasant. Use running cold water forseveral minutes on anyone who gets scalded.


Type Purpose DifferentiationPractical Pupils revise energy transfers and are introduced to energy conservation. Core

I-Technician.qxd 08-Jun-04 2:54 PM Page 1

I1aActivity

CoreEnergy transfers

You are going to observe five processes and think about theenergy transfers taking place.

Obtaining evidence

1 Boil the kettle of water and let it cool.2 Answer Questions 1 – 4 for the hot water in the kettle.3 Blow the whistle. (Don’t forget to disinfect it first.)4 Answer Questions 1 – 4 for blowing the whistle.5 Close the switch to light the lamp. Watch it glowing.6 Answer Questions 1 – 4 for the glowing light bulb.7 Lift up the ball and drop it. (Don’t forget to pick it up again.)8 Answer Questions 1 – 4 for the falling ball.9 Wind up the clockwork toy. Let it wind down.10 Answer Questions 1 – 4 for winding up the toy.

Considering the evidence

1 Where did the energy come from?2 Where did the energy end up?3 For each process, focus on one energy transfer that is

happening.

Draw a diagram of that energy transfer, using arrows marked‘energy transferred as energy’ and boxesmarked ‘energy stored as energy’.

4 How useful is the energy at the end of the process? Explainyour answer.


A B C D E

a kettlecooling

blowinga whistle

lighting a lamp

droppinga ball

winding upa clockwork

toy

Steam orhot waterfrom the

kettle can burn.Disinfect the whistlebefore using.

I-Activities.qxd 08-Jun-04 2:50 PM Page 1

I1bTeacher

activity notesWasted energy


Type Purpose DifferentiationPaper To help pupils to realise that not all the energy ends up where we want it when energy

is transferred.Core

Running the activityPupils answer the questions on the sheet.


PitfallsPupils may focus on minor energy uses such as the car battery or hand moving the hairdryer.

Answers1 Electrical energy.2 Movement/kinetic energy, heat/thermal energy, sound energy3

4 Drying wet hair.5 Heat energy, movement energy.6 Sound energy.7 Chemical energy (in petrol/diesel fuel).8 Movement/kinetic energy, heat/thermal energy, sound energy.

9

10 move11 Movement/kinetic energy.12 Heat/thermal energy, sound energy.

electrical energy

heat energy

sound energy

kinetic/movement

energy

heat energy

heat energy

sound energy

movement energy


I1bActivity

CoreWasted energy

When energy is transferred, where does it all go?You are going to think about some everyday devices.


1 What type of energy goes into a hairdryer?2 What three types of energy come out of a hairdryer?3 Draw an energy transfer diagram for a hairdryer.4 What do you use a hairdryer for?5 What types of energy do you want from a hairdryer?6 What unwanted energy comes out of a hairdryer?

7 What type of energy goes into a car?8 What types of energy come out of a car?9 Draw an energy transfer diagram for a car.10 What does a car do?11 What type of energy do you want from a car?12 What unwanted energy comes from a car?



I2aTeacher

activity notesInvestigating voltage: Batteries

Running the activityPupils work in pairs or small groups.

Pupils make a prediction about how the voltage will change as they add more batteries toa circuit. They build circuits from circuit diagrams, and are given a table format forrecording their results. They draw a line graph and analyse their results. Pupils are askedto use their graph to predict the outcome of a further experiment.

Other relevant materialSkill sheet 35: Reading a voltmeter

Expected outcomesAs the number of batteries is increased the voltage will increase. If the batteries are newenough to be fully charged, then each one will increase the voltage by 1.5V; otherwiseeach one will increase the voltage by an amount between 0V and 1.5V.

PitfallsEnsure that pupils do not use too many batteries, or they will ‘blow’ the lamp. For five1.5V batteries, the lamp used needs to be >7.5V, probably 12V. The lamp will not glowwhen one battery is used, but the voltage will register on the voltmeter. Pupils will onlyget a straight line graph if the batteries are new.

Answers1 The voltage will increase with the number of batteries.

2 If there are more batteries more energy is being put into the circuit, so there will bemore voltage.

3 It increased (should have done).

4 Depends on pupil’s response to Question 1.

5 Pupils should extrapolate the graph to six batteries, and read off the voltage.

6 Depends on pupils’ results. A flat battery might have given little or no increase involtage.

7 Depends on answer to Question 6. Use new batteries for the experiment.


Type Purpose DifferentiationPractical Pupils see how the voltage changes when the number of batteries in a circuit is increased:

more batteries means more energy being sent out, which means more voltage.Core


I2aTechnician

activity notesInvestigating voltage: Batteries

EquipmentFor each pair or group:

� five batteries� lamp (12 V)� voltmeter� eight leads


For your informationRunning the activityPupils work in pairs or small groups.

Pupils make a prediction about how the voltage will change as they add morebatteries to a circuit. They build circuits from circuit diagrams, and are given atable format for recording their results. They draw a line graph and analysetheir results. Pupils are asked to use their graph to predict the outcome of afurther experiment.

Expected outcomesAs the number of batteries is increased the voltage will increase. If the batteriesare new enough to be fully charged, then each one will increase the voltage by1.5 V; otherwise each one will increase the voltage by an amount between 0 Vand 1.5 V.

PitfallsEnsure that pupils do not use too many batteries, or they will ‘blow’ the lamp.For five 1.5 V batteries, the lamp used needs to be >7.5 V, probably 12 V. Thelamp will not glow when one battery is used, but the voltage will register onthe voltmeter. Pupils will only get a straight line graph if the batteries are new.


Type Purpose DifferentiationPractical Pupils see how the voltage changes when the number of batteries in a circuit is increased:

more batteries means more energy being sent out, which means more voltage.Core


I2aActivity

CoreInvestigating voltage: Batteries

You are going to increase the number of batteries in a circuitand see how this changes the voltage.

Equipment

� five batteries � a voltmeter� a lamp � eight leads

Planning and predicting

1 Look at the circuit above. Make a prediction about how thevoltage will change as you add more batteries to the circuit.

2 Explain your reasons.

Obtaining evidence

1 Make a table like the one shown here to recordyour results.

2 Build the circuit shown above. Measure thevoltage.

3 Add another battery to the circuit, as shownbelow the table. Measure the voltage.

4 Repeat the experiment with three, four and five batteries.


5 Draw a line graph of your results. Put number of batteriesalong the bottom and voltage up the side. Draw a line of bestfit using a ruler.

3 How did the voltage change when you added extra batteries?4 Was your prediction correct?5 Use your graph to suggest the voltage when there are six

batteries in the circuit.

Evaluating

6 Were any of your results not as you expected?7 If so, how could you improve your experiment?


V

Number of 1 2 3 4 5batteries

Voltage (V)

V


I2bTeacher

activity notesInvestigating voltage: Components

Running the activityPupils work in pairs or small groups. They build a series circuit with two lampsand measure the battery voltage and the voltage across each lamp.


Expected outcomesThe voltage is often different across the components in a series circuit, but addsup to give the voltage across the battery.

PitfallsSome pupils have difficulty connecting a voltmeter correctly. If the circuit is lefton for a long time the battery voltage may drop, so that the final voltagereading is low, and the voltages do not add up. Warn pupils not to leave thecircuit on except when they are measuring the voltage.

ICT opportunitiesA useful piece of software for making circuits is available on the CD-ROMCrocodile Clips (Crocodile Clips Ltd). Crocodile Clips 3 Elementary can bedownloaded free of charge from the Crocodile Clips website.

Answers1 It is different across different places around the series circuit. The sum of

the voltages across each of the components is the same as the voltage acrossthe battery.


Type Purpose DifferentiationPractical To show pupils how to wire series circuits, and to measure voltage across different

points in series circuits.Core


http://www.heinemann.co.uk/hotlinks/url.asp?urlid=9601

I2bTechnician

activity notesInvestigating voltage:Components

EquipmentFor each group:

� a battery� two lamps� a voltmeter� six leads


For your informationRunning the activityPupils work in pairs or small groups. They build a series circuit with two lampsand measure the battery voltage and the voltage across each lamp.

Expected outcomesThe voltage is often different across the components in a series circuit, but addsup to give the voltage across the battery.

PitfallsSome pupils have difficulty connecting a voltmeter correctly. If the circuit is lefton for a long time the battery voltage may drop, so that the final voltagereading is low, and the voltages do not add up. Warn pupils not to leave thecircuit on except when they are measuring the voltage.

ICT opportunitiesA useful piece of software for making circuits is available on the CD-ROMCrocodile Clips (Crocodile Clips Ltd). Crocodile Clips 3 Elementary can bedownloaded free of charge from the Crocodile Clips website.


Type Purpose DifferentiationPractical To show pupils how to wire series circuits, and to measure voltage across different

points in series circuits.Core


http://www.heinemann.co.uk/hotlinks/url.asp?urlid=9371

I2bActivity

CoreInvestigating voltage:Components

You are going to build a series circuit and measure the voltageacross three different places.

Equipment

� a battery� two lamps� a voltmeter� six leads

Obtaining evidence

1 Make a table like the one shown here torecord your results.

2 Build a simple series circuit with twolamps as shown in this diagram:

3 Measure the voltage across the battery.4 Move the voltmeter, as shown below, and measure the voltage across one lamp:

5 Move the voltmeter and measure the voltage across the other lamp:


1 What did you find out about voltage across the components in a series circuit?


V

V

V

Circuit Voltage (V)

Series, across battery

Series, across one lamp

Series, across other lamp


I2dTeacher

activity notesInvestigate: How to increase thevoltage in a fruit cell

Running the activityPupils plan an investigation to find out how they can maximise the voltage from a cell made of a fruit or vegetable by changing the two different electrode metals. They consider the othervariables (fruit chosen, distance between electrodes, size of electrodes, shape of electrodes). Theycarry out their experiment, measuring and recording voltage for different pairs of metals. Theydecide which pair of metals gave the highest voltage and evaluate their experiments.

Core: They are told that two of the variables are the pair of metals used (e.g. pairs frommagnesium, zinc, copper, iron) and the fruit or vegetable. They are asked for three other factorsconcerning the metals, i.e. size of metal pieces, shape, and the distance between the metal pieces.They carry out their investigation, analyse their results and evaluate their experiments.

Help: This has additional questions for pupils asking them to consider each variable in turn andalso provides a results table.


Expected outcomesMagnesium and copper will probably give the best results – about 1.5V.

PitfallsFruit such as lemons will work best if they are rolled and squeezed in the hands before insertingthe electrodes so that the insides are broken up and the juice released.

Two electrodes of the same metal should give zero voltage (a pair of the same metal is aworthwhile test). The greater the difference in reactivity of the metals, the greater the voltage.(Reactivity series: magnesium, aluminium, zinc, iron, lead, copper.) If pupils use magnesium andcopper and get the highest voltage they may assume this is due to the magnesium or to thecopper rather than the difference. Encourage them to try magnesium with aluminium andcopper with lead to see that this is not the case.

Safety notesCheck pupils’ plans for health and safety before work begins.

Pupils will need to make an incision in the fruit or vegetable for the softer metals to be pushedinto. Show them how to do this safely.

ICT opportunitiesPupils could search the Internet for ‘lemon batteries’. There are many sites giving interestingapplications of these.

AnswersCore:

1 varies; 2 varies; 3 Use a voltmeter; 4 Size and shape of metal, distance between piecesof metal; 5 Use pieces of same size and shape, put in the same holes in the fruit; 6 yes;7 Depends on pairs tried; 8 varies; 9 varies

Help:

1 varies; 2 varies; 3 Use a voltmeter; 4 yes; 5 yes; 6 yes; 7 yes; 8 Depends on pairs tried;9 varies


Type Purpose DifferentiationPractical Pupils plan and carry out an investigation to find out which two metals will produce the

highest voltage from a fruit or vegetable cell.Core, Help


I2dTechnician

activity notesInvestigate: How to increase the voltage in a fruit cell

EquipmentFor each group:

� lemons, potatoes, apples, oranges or other similar fruits or vegetables (lemon juice or vinegar could beused instead)

� pieces of metal of the same size and shape: magnesium, aluminium, zinc, iron, lead, copper� voltmeter� connecting leads with crocodile clips� ruler� scalpel or craft knife with guard


For your informationRunning the activityPupils plan an investigation to find out how they can maximise the voltage from a cell made of a fruit orvegetable by changing the two different electrode metals. They consider the other variables (fruit chosen,distance between electrodes, size of electrodes, shape of electrodes). They carry out their experiment,measuring and recording voltage for different pairs of metals. They decide which pair of metals gave thehighest voltage and evaluate their experiments.

Core: They are told that two of the variables are the pair of metals used (e.g. pairs from magnesium, zinc,copper, iron) and the fruit or vegetable. They are asked for three other factors concerning the metals, i.e.size of metal pieces, shape, and the distance between the metal pieces. They carry out their investigation,analyse their results and evaluate their experiments.

Help: This has additional questions for pupils asking them to consider each variable in turn and alsoprovides a results table.

Expected outcomesMagnesium and copper will probably give the best results – about 1.5 V.

PitfallsFruit such as lemons will work best if they are rolled and squeezed in the hands before inserting theelectrodes so that the insides are broken up and the juice released.

Two electrodes of the same metal should give zero voltage (a pair of the same metal is a worthwhile test).The greater the difference in reactivity of the metals, the greater the voltage. (Reactivity series: magnesium,aluminium, zinc, iron, lead, copper.) If pupils use magnesium and copper and get the highest voltage theymay assume this is due to the magnesium or to the copper rather than the difference. Encourage them totry magnesium with aluminium and copper with lead to see that this is not the case.

Safety notesCheck pupils’ plans for health and safety before work begins.

Pupils will need to make an incision in the fruit or vegetable for the softer metals to be pushed into. Showthem how to do this safely.

ICT opportunitiesPupils could search the Internet for ‘lemon batteries’. There are many sites giving interesting applicationsof these.


Type Purpose DifferentiationPractical Pupils plan and carry out an investigation to find out which two metals will produce the

highest voltage from a fruit or vegetable cell.Core, Help


I2dActivity

CoreInvestigate: How to increase thevoltage in a fruit cell

You are going to plan and carry out an investigation to find outwhich two metals will produce the highest voltage from a fruit or vegetable cell. This potato cell produces enough voltage tolight a lamp.

Equipment

� fruits or vegetables, or a beaker of lemon juice� pieces of metal of the same size and shape:

magnesium, aluminium, zinc, iron, lead, copper� scalpel or knife with guard� voltmeter� connecting leads with crocodile clips� ruler


1 Discuss with your group your plan for the experiment.You are going to experiment with different pairs of metals, A and B, in the cell.

1 Which pairs of metals are you going to use?2 Which fruit or vegetable will you use?3 How will you measure the voltage being produced by the fruit or

vegetable cell?4 What three other factors about the pieces of metal (other than the

type of metal) could change the voltage?5 How will you make sure these stay the same?

Obtaining evidence

2 Draw up a results table.3 Carry out your experiment. Record your results.


6 Did the different pairs of metals give different voltages?7 If so, which pair produced the biggest voltage?

Evaluating

8 Did you take into account all the factors that change the voltage?9 Would you change your experiment if you were going to do it

again? If so, how?


Do nottaste thefruits orvegetables.

metal A metal B

potato

0 10 20 30 40 50 60 70 80 90 100

lemon

metal

ruler


You are going to plan and carry out an investigation to find outwhich two metals will produce the highest voltage from a fruitor vegetable cell. This potato cell produces enough voltage tolight a lamp.


1 Discuss with your group your plan for theexperiment.You are going to experiment with different pairs of metals, A and B, in the cell.

1 Which pairs of metals are you going to use?2 Which fruit or vegetable will you use?3 How will you measure the voltage being

produced by the fruit or vegetable cell?4 Does the fruit or vegetable need to be the

same each time?5 Will it matter if the pieces of metal are the same size and shape?6 Will it matter how far apart the pieces of metal are?

Obtaining evidence

2 Draw up a table to record your results like this:

3 Carry out your experiment.


7 Did the different pairs of metals give different voltages?8 If so, which pair produced the biggest voltage?

Evaluating

9 Would you change your experiment if you were going to do itagain? If so, what would you change? And why?

Consider:� The fruit you used. � How you measured the voltage.� The size and position of the pieces of metals. � The pairs of metals you chose.

I2dActivity

HelpInvestigate: How to increase thevoltage in a fruit cell


Do nottaste thefruits orvegetables.

metal A metal B

potato

0 10 20 30 40 50 60 70 80 90 100

lemon

metal

ruler

Metal A Metal B Voltage (V)

zinc iron


I2eTeacher

activity notesInvestigate: Voltage in alemon battery

Running the activityIf pupils have not seen a ‘lemon battery’ you may decide to demonstrate one.(For details, see Activity I2d.) Pupils work with the data on the Activity sheet toproduce a graph of the voltage produced against the length of the copper stripthat was inside the lemon. The results will give a best-fit straight line in theregion 0.5cm to 2.5cm.

Core: Pupils plot the graph on graph paper. The required axes are drawn on theActivity sheet.

Other relevant materialSkill sheet 5: Drawing charts and graphs

PitfallsThe voltage rises steeply as soon as the foil touches the lemon and the straightline behaviour is only between 0.5cm and 2.5cm. If pupils include the originin their graphs, they need to realise that this will not lie on the straight line. If they don’t include the origin on a graph they sometimes make the mistake of treating the intersection of the axes as an origin and force the line throughthis point.

Note: the voltage in this experiment reached a maximum of 1.47V at 3.0cm.

ICT opportunitiesPupils could search the Internet for ‘lemon batteries’. There are many sitesgiving interesting applications of these.

AnswersCore:

1 As the length of the copper foil in the lemon increases the voltage willincrease.

2 (graph)

3 (straight line between 0.5 cm and 2 cm)

4 As the length of the copper foil in the lemon increased the voltageincreased linearly/in even steps (may say after initial 0–5 cm).

5 No. Eventually a maximum will be reached as the magnesium and strengthof lemon are not being increased (or other sensible reason).


Type Purpose DifferentiationPaper Pupils plot a graph of results of an experiment to find out if the voltage produced by a

‘lemon battery’ depends on the size of the metal electrodes.Core


I2eActivity

CoreInvestigate: Voltage in a lemonbattery

You are going to try to find out if the voltage produced by a‘lemon battery’ depends on the size of the metal electrodes.


Chris and Charlie set up a lemon battery with a pieceof magnesium ribbon and a piece of copper foil markedin 0.5 cm steps.

1 Predict what will happen as the copperfoil is pushed further into the lemon.

Obtaining evidence

Chris connects the circuit, but keeps thecopper foil out of the lemon. There is novoltage. Then Chris pushes the copperinto the lemon, half a centimetre at atime. Charlie writes down the voltagereadings.

Presenting the results

2 Plot a graph of voltage againstlength of foil on axes like the ones shown below.

3 Draw a best-fit straight line through the points over the range 0.5 cm to 2.0 cm.


4 Describe how the voltage changedas the length of the copper foil inthe lemon changed.

5 Do you think the voltage wouldhave continued to go up as morecopper was pushed into thelemon? Explain your answer.


lemon

magnesiumribbon

copperfoil

0.5 cm

0

1

2v

Length of copper foil in Voltage (V)lemon (cm)

0.5 1.25

1.0 1.31

1.5 1.37

2.0 1.43

2.5 1.47

Vo

ltag

e (V

)

Length (cm)


I3aTeacher

activity notesUsing electricity

Running the activityPupils plug a mains appliance into the joulemeter and measure the energy for 100s. Thismay involve counting flashes for every 100J or reading the display, depending on thejoulemeter.

How the experiment is organised will depend on the number of joulemeters available. Onecould be used to demonstrate the experiment, or to perform a class experiment where eachgroup in turn measures the energy for one appliance. This could be done with the othergroups watching and copying down the results, or involved in some other activity until allthe groups have made one measurement, whereupon the whole class can copy all theresults.

Electrical appliances could include 18W and 60W bulbs that are claimed to give the samelight output. Lighting and heating devices, music or computing equipment will give arange of values.

Expected outcomesPupils record energy use in joules. They compare appliances and see that heatingappliances use the most energy or that energy-saving bulbs use less than conventionalbulbs, depending on appliances used.

PitfallsResults should be proportional to power ratings, except where the power rating is amaximum and the actual use did not reach the maximum use (e.g. three-position switchfan heater on minimum position only).

Some pupils confuse an ammeter with a joulemeter. Take care to point out the difference(current in amps and energy in joules) – not least that the joulemeter reading depends onthe time over which the measurement is made.

Safety notesSome of the mains appliances will get very hot. All mains equipment used should havepassed a recent portable appliance test (PAT) and should not be brought in from home orelsewhere.

ICT opportunitiesIt would be possible to set up a spreadsheet for the results which would calculate cost(multiply energy in joules by cost of a unit (a kilowatthour: about 7p) divided by3600000).

Answers1 varies

2 varies

3 varies

4 If the power rating is in watts (not kilowatts), the energy value for 100s will be100 times the power rating, for example for items like light bulbs, which use 60W allthe time. For items that switch on and off, e.g. those with thermostats, this will not betrue. In general high power rating should give higher energy use.


Type Purpose DifferentiationPractical Pupils measure the energy used by different electrical appliances Core


I3aTechnician

activity notesUsing electricity

EquipmentFor each group (if available):

� joulemeter� stopwatch� electrical appliances

Otherwise, demonstration, perhaps with one electrical appliance for eachgroup.

For your informationRunning the activityPupils plug a mains appliance into the joulemeter and measure the energy for100 s. This may involve counting flashes for every 100 J or reading the display,depending on the joulemeter.

How the experiment is organised will depend on the number of joulemetersavailable. One could be used to demonstrate the experiment, or to perform aclass experiment where each group in turn measures the energy for oneappliance. This could be done with the other groups watching and copyingdown the results, or involved in some other activity until all the groups havemade one measurement, whereupon the whole class can copy all the results.

Electrical appliances could include 18 W and 60 W bulbs that are claimed togive the same light output. Lighting and heating devices, music or computingequipment will give a range of values.

Expected outcomesPupils record energy use in joules. They compare appliances and see thatheating appliances use the most energy or that energy-saving bulbs use lessthan conventional bulbs, depending on appliances used.

PitfallsResults should be proportional to power ratings, except where the power ratingis a maximum and the actual use did not reach the maximum use (e.g. three-position switch fan heater on minimum position only).

Some pupils confuse an ammeter with a joulemeter. Take care to point out thedifference (current in amps and energy in joules) – not least that the joulemeterreading depends on the time over which the measurement is made.

Safety notesSome of the mains appliances will get very hot. All mains equipment usedshould have passed a recent portable appliance test (PAT) and should not bebrought in from home or elsewhere.

ICT opportunitiesIt would be possible to set up a spreadsheet for the results which wouldcalculate cost (multiply energy in joules by cost of a unit (a kilowatthour: about 7p) divided by 3 600 000).


Type Purpose DifferentiationPractical Pupils measure the energy used by different electrical appliances Core


I3aActivity

CoreUsing electricity

You are going to measure the energy used by different electricalappliances.

Equipment

� joulemeter� stopwatch� electrical appliances


1 Which appliances do you think will use the most energy? Which will use the least? Or do you think they will all use the same?

Obtaining evidence

1 Copy this table for your results.

2 Find the power rating of the appliance. (It will be in watts (W)or kilowatts (kW).) Record it in the table.

3 Connect the appliance to the joulemeter.4 Switch on the stopwatch and the appliance together. (How

will you do this?)5 Measure the energy used in joules in 100 s (1 minute and 40 s).6 Record your results in the table.


2 Which appliance used the most energy in 100 s?3 Which appliance used the least energy in 100 s?4 Can you see any pattern between the power rating and the

energy used?


MAIN OUTPUT13 Amp Minimum

MAINS JOULEMETER

light bulb

stopwatch

Pulse

TIMING OUTPUT

100 JOULES PER FLASH

1000 JOULES PER FLASH

DISCONNECT THE MAINS PLUG FROMTHE SUPPLY SOCKET WHEN NOT IN USE

Take carewith mainsappliances.

Some will get veryhot.

Appliance Energy used in Power rating of 100 seconds (J) appliance (W)


I3bTeacher

activity notesUsing Sankey diagrams

Running the activityPupils study three Sankey diagrams and answer questions about them. Pupils complete thetasks on the Activity sheet and realise (a) that only a very small percentage of the energyusually ends up where you want it, and (b) the energy ends up as thermal energy spreadacross millions of particles and is therefore no longer useful.

Other relevant materialSkill sheet 36: Sankey diagrams

AnswersA filament lamp

1 5%

2 95%

3 Dissipated to the surroundings, shared between billions of particles (in air and objectsaround).

4 no

A television

1 8%

2 92%


4 no

A kettle

1 90%

2 10%


4 no


Type Purpose DifferentiationPaper The most able pupils reinforce their understanding of energy conservation and

dissipation.Extension

I-Teachers.qxd 21-Jul-04 4:10 PM Page 9

I3bActivity

ExtensionUsing Sankey diagrams

You are going to consider where the energy ends up and howuseful it is.


Study each of the three Sankey diagrams. For each one:

1 Calculate the percentage of the input energy that ends upwhere it is wanted.

2 Calculate the percentage of input energy that ends up where it is not wanted.

3 Describe in your own words where most of the energy ends up.

4 Can this energy be transferred again in a useful way?


100 J as chemical energy

in the battery

5 J as thermal energy from the wires 90 J as

thermal energy from the lamp

5 J as light energy

from the lamp

A filament lamp

5 MJ as light energy

92 MJ as thermal energy

100 MJ aselectricalenergy

3 MJ as sound energyA television

40 kJ asthermal energyin surroundingair and kettle

400 kJ aselectrical energy

360 kJ asthermal energy

in water

A kettle


I4aTeacher

activity notesInside a power station

Running the activityThe apparatus for each demonstration is given on the Activity sheets.

Turning a turbineThis shows how the chemical energy stored in methane and oxygen can be used to createa rotary motion. A Bunsen burner is used to heat water. The water is in a conical flask wherethe only exit is a nozzle-shaped glass tube. When the water boils, steam is produced.The steam rushes out of the nozzle and turns the vanes of a small fan.

Lighting a lampThis uses a dynamo lighting a bulb to show how a rotary motion can be used to generate electricity.

Core: Pupils use the questions on the Activity sheet to relate the demonstrations to theworkings of the power station.

Help: Pupils colour diagrams of a power station and both sets of apparatus, to help themrelate the demonstrations to the working of a power station.

Extension: Pupils explain what the demonstrations show and how they relate to a power station,then go on to write an energy transfer diagram and think about wasted energy.

Expected outcomesThe turbine turns and the bulbs light up. Pupils relate these observations to what happens in a power station.

PitfallsPupils will be unfamiliar with boilers, turbines and generators, which makes the activityrather alien and ‘uninvolving’. If possible, pupils should be shown a short video about apower station or, better, pupils should visit a power station.

Safety notesThe jet of steam driving the turbine presents a minimal hazard as long as the boiling is nottoo vigorous. Make sure the nozzle is not blocked, as this is the only opening.

Scalds from steam are particularly unpleasant. Use running cold water for several minuteson anyone who gets scalded.

AnswersCore:

1 Water evaporates/turns into steam.

2 Particles in steam are far apart, while in water they are close together.

3 The turbine turns.

4 The generator.

5 A person.

6 electricity

7 The lamp lights up.

8 Both the generator and the dynamo make electricity when they spin.

9 Chemical, thermal, kinetic, kinetic, kinetic, electrical.


Type Purpose DifferentiationPractical Pupils observe two demonstrations and relate them to the energy transfers that happen

in a power station burning fossil fuels.Core, Help, Extension


I4aTeacher

activity notesInside a power station (continued)

Help:

Additions in colour to diagrams:

� boiler and Bunsen red� flames orange� water in conical flask and pipe blue� blue arrows from boiler to turbine in diagram A and out of nozzle in

diagram B.� turbines yellow� dynamo and generator green

1 electricity

2 Chemical, heat, movement, movement, electrical.

Extension:

1 For example: The chemical energy in the fuel and oxygen is transferred intothermal energy during burning. The thermal energy is transferred to the waterparticles. The water evaporates. It expands as it evaporates because theparticles are much further apart in a gas than in a liquid. The fast-movingsteam particles hit the vanes of the turbine, making it turn.

2 generator

3 For example: Turning the handle spins the dynamo. When the dynamo spinselectricity is made, which carries energy to the lamp and makes it light up.In a power station the spinning turbine turns the generator which, like thedynamo, makes electricity.

4 Chemical, thermal, kinetic, kinetic, kinetic, electrical.

5 Thermal energy lost when the fuel is burning, friction in all the movingparts (also some sound, and kinetic energy as vibrations).



I4aTechnician

activity notesInside a power station

EquipmentFor the teacher demonstrations:

Turning a turbine

� Bunsen burner, tripod, mat and gauze� conical flask with bung and glass nozzle as shown� small fan

Lighting a lamp

� dynamo as shown in diagram

For your informationRunning the activityThe apparatus for each demonstration is given on the Activitysheets.

Turning a turbineThis shows how the chemical energy stored in methane and oxygen can be used to create a rotarymotion. A Bunsen burner is used to heat water. The water is in a conical flask where the only exit is anozzle-shaped glass tube. When the water boils, steam is produced. The steam rushes out of the nozzle and turns the vanes of a small fan.

Lighting a lampThis uses a dynamo lighting a bulb to show how a rotarymotion can be used to generate electricity.

Core: Pupils use the questions on the Activity sheet to relate the demonstrationsto the workings of the power station.

Help: Pupils colour diagrams of a power station and both sets of apparatus, to help them relate the demonstrations to the working of a power station.

Extension: Pupils explain what the demonstrations show and how they relate toa power station, then go on to write an energy transfer diagram and thinkabout wasted energy.

Expected outcomesThe turbine turns and the bulbs light up. Pupils relate these observations towhat happens in a power station.

PitfallsPupils will be unfamiliar with boilers, turbines and generators, which makes theactivity rather alien and ‘uninvolving’. If possible, pupils should be shown ashort video about a power station or, better, pupils should visit a power station.

Safety notesThe jet of steam driving the turbine presents a minimal hazard as long as theboiling is not too vigorous. Make sure the nozzle is not blocked, as this is theonly opening. Scalds from steam are particularly unpleasant. Use running coldwater for several minutes on anyone who gets scalded.


Type Purpose DifferentiationPractical Pupils observe two demonstrations and relate them to the energy transfers that happen

in a power station burning fossil fuels.Core, Help, Extension

water

nozzleturbine

dynamo


I4aActivity

CoreInside a power station

You are going to watch two demonstrations. The first showshow methane can be used to turn a turbine. The secondshows how a spinning turbine can make electricity.

You are going to think about how these things are done in apower station.


Turning a turbine

1 What happens to the water when it is heated?2 Explain why the steam takes up much more space

than the water and rushes out of the nozzle.3 What happens when the jet of steam hits the turbine?4 In a power station, what does the turbine turn?

Lighting a lamp

5 What turns the dynamo?6 What is made in the dynamo?7 How do you know?8 How is a generator in a power station like

the dynamo in this demonstration?9 Copy and complete this energy transfer

diagram.


water

nozzleturbine

energyin fuel

wateror

steamenergy turbineenergy

generatoror

dynamo

handle of dynamo

energy

energy

energy

................................................ ........................ ........................ ........................

........................

dynamo


I4aActivity

HelpInside a power station




Turning a turbine

1 Look carefully at diagrams A and B. You are going tohighlight parts of bothdiagrams in colour.

The fuel is burned.

2 Outline the places where the fuel is burned in red.3 Colour the flames orange.

Burning fuel heats the water, which turns to steam.

4 Colour the water blue.5 Add blue arrows to show the steam moving.

The rushing steam turns the turbine.

6 Colour the turbines yellow.

Lighting a lamp

7 Look carefully at diagrams A and C. You are going to highlight parts of both diagrams in colour.

The handle turns the dynamo.

8 Colour the generator and the dynamo green.

The lamp lights up.

1 The generator and the dynamo make

.2 Fill in the gaps on diagram A using these

types of energy:

(Hint: one of them is used more than once.)


energy in fuel

energy energy energy

energy

boilerturbine generatorA

B

water

nozzleturbine

C dynamo

heatchemicalelectricalmovement


I4aActivity

ExtensionInside a power station




Turning a turbine

1 Explain how burning the fuel makes the turbine turn. Include each of the following words in your explanation at least once.

energy particles expand evaporatethermal chemical kinetic

2 In a power station, what does the turbine turn?

Lighting a lamp

3 Explain how turning the handle makes the lamplight up, and how this is like what happens in apower station. Include each of the following wordsin your explanation.

dynamo electricity generator turbine

4 Copy and complete this energy transfer diagram.Leave space above and below the diagram.


water

nozzleturbine

energyin fuel

wateror

steamenergy turbineenergy

generatoror

dynamo

handle of dynamo

energy

energy

energy

................................................ ........................ ........................ ........................

........................

dynamo

5 Think about where and how energy is wasted.On your energy transfer diagram, draw extraarrows showing wasted energy. Label thearrows to show how the energy is wasted.

Only some of the energy in the fuel ends upin the electricity.


I4bTeacher

activity notesComparing power stations


Type Purpose DifferentiationDiscussion Pupils investigate one type of power station and pool results with the rest of the class. Core

Running the activityProvide material such as books, leaflets and access to the Internet so that pupils can research one type ofpower generation. Allocate a suitable power station type to each group, taking into account:

1 The type of resources – if they are clear and simple to follow, or require good reading skills.

2 The number of groups and types of power station it is most important to cover. For example, for sixgroups you could choose: coal, gas, hydroelectric, wind, solar and nuclear. You might provide twoentries for the table already filled in, e.g. biomass and tidal, as shown:

Information will depend on what is available.

The table could be built up by pupils themselves, typing into a computer. You could print/copy the tablefor each pupil. Pupils then use the table to decide the appropriate power station in each of the questions.

Expected outcomesPupils investigate one type of power station in some detail and consider a summary of other types of powerstation.

PitfallsThis could expand into several lessons. Remind pupils on the points they are trying to find out, andprovide clear and succinct resources.

Answers1 solar

2 wind

3 Fossil fuels (depending on supplies), maybe nuclear, or a mixture.

4 hydroelectric

Type of Fuel/land Pollution Other side Serious Effect on Lots ofpower needed effects accident locals powerstation risks available?

biomass fields for crop smoke and change of possibly fire many delivery possible if(e.g. willow) gases from land use to or delivery lorries (and technologyor animal burning fuel produce fuel truck crash smell if dung) improves(dung) but lots of

jobs and fields

tidal estuary with none? loss of flooding? loss of no, aslarge tidal habitat – fishing? limitedrange effect on number

birds of sites available


I4bActivity

CoreComparing power stations

With the help of the whole class you are going to build up a table comparing the features of different types of power stations.

Equipment

� books or leaflets on all types of power generation� access to the Internet


1 Note which type of power generation your teacher asks your group to investigate:

Obtaining evidence

2 Use the resources available to make notes answering the following questions:

� What fuel, type of land, other resources are needed to run the power station?� What pollution is produced?� Are there other effects on the environment?� What accidents might occur?� How will the power station affect the local population?� Can one power station generate a lot of power? (Would we need a lot of them?)

Presenting the results

3 Enter the results for your group in the table for the whole class.


4 Use the table for the whole class to decide the type of power station that would bebest for each location:

1 A sunny island with no fossil fuels and lots of holiday hotels that want airconditioning.

2 A remote fishing village on the Atlantic coast, miles from any town.3 A big city with lots of manufacturing industry and businesses.4 A large city built near a large river which flows from nearby mountains.


� coal� oil� gas� wave� tidal

� wind� solar� geothermal� biomass� nuclear



I1 PlenariesMake it work

Review learning� Pupils work through the sheet making choices and giving

two reasons for each choice.

� Pupils share their reasons with the class.

Teacher note: Especially in case of towel and washing line,some may prefer not to use electricity. There are NO rightand wrong answers. The exercise is simply to see thatelectricity often has advantages (and different advantages)and lots of people like to use it. It does also havedisadvantages – some of which may be suggested.

Sharing responses� Pupils compare their answers to the questions for each of

the appliances.

Group feedback� Challenge pupils to write the longest energy transfer

chain they can, which includes electrical energy. To showpupils what you mean, give a verbal example of one thatdoesn’t contain electricity: e.g. A wind up toy: Sunlight,chemical in plant, chemical in animal, chemical inhuman, kinetic in human, elastic potential in spring,kinetic in clockwork toy, thermal and sound in air, toyand ground

Word game� Pupils complete the acrostic to remind themselves of

types of energy.

Looking ahead� Set up a series circuit with a battery, two lamps and a

switch. The energy comes from the battery, which ismarked with a voltage.

� Explain that you want to measure the voltage across thebattery and each of the lamps. Show pupils how youconnect the voltmeter across the battery and read thevoltage. Repeat this across one lamp, and then the otherlamp. Explain that you always measure voltages acrosscomponents (not through the component, as with currents). Show the symbol for a voltmeter and explain that voltage is measured in volts.

➔ Pupil sheet

AnswersElectricity is easy to use; clean (at point ofuse); quick; requires less effort from user.There may be reasons for using othermethods in some circumstances, e.g.candles give a dancing, coloured light(romantic). Note that in remote areasbatteries or generators are often used inpreference to doing without electricity.

AnswersThese will vary, but could be: Toasting aslice of bread: Sun, light, chemical inplant, chemical in coal, heat in burningcoal, heat in steam, kinetic in generators,electrical in wires, heat in toaster.

➔ Pupil sheet

Answers1 kinetic; 2 sound; 3 elastic; 4 electrical; 5 light; 6 potential; 7 thermal; 8 gravitational; 9 chemical. Word down is: energetic.

Equipmentbattery (e.g. two 1.5 V batteries in aholder) or power supply; two lamps in holders; connecting leads; switch; avoltmeter (same as pupils will be usingnext lesson)


Review learning

Pupils look at alternativesto electricity (e.g. candleinstead of light bulb) toremind themselves ofadvantages of electricity.

Sharing responses

In pairs, pupils take turnsto go through their answersto Activity I1a.

Group feedback

Challenge groups to writethe longest chain of energytransfers, includingelectrical, that they canthink of.

Word game

Check progress using anacrostic about differenttypes of energy.

Looking ahead

Show pupils the symbol fora voltmeter and show themhow to add one to a circuit.

I-Plenaries.qxd 08-Jun-04 4:27 PM Page 1


Review learning

To solve each problem below, make a choice, A or B, and give two different reasons for your choice.

1 It is very cold.

A Switch on a fan heater.

B Light a coal fire.

2 You want a hot drink.

A Use an electric kettle to boil water.

B Light a fire and use it to boil a kettleof water.

3 Your hair is wet.

A Use a hairdryer to dry it.

B Use a towel to dry it.

4 It is getting dark.

A Switch on electric lights.

B Light some candles.

5 Your clothes are creased.

A Use an electric iron.

B Heat an old-fashioned iron onthe fire and use it.

6 Your clothes are wet.

A Put them in the tumble dryer.

B Hang them on the line.


fan heater coal fire

hairdryergirl drying hair with a towel

electric lightbulb candle

electric jug kettle kettle over campfire

electric ironold-fashioned

flat iron

tumble dryerwashing on the line



Sheet 1 of 1

Sheet 1 of 1


PlenariesI1 Make it work


Word game

Fill in the energy forms using the clues, and find the hidden word.

find the word

⇓

1

2

4

5

6

7

3

9

8

1 moving2 You can hear this.3 In a spring.4 In a circuit.5 From the Sun.6 stored7 Wasted energy often takes this

form.8 More at the top of the hill.9 In a battery.

Word game

Fill in the energy forms using the clues, and find the hidden word.

find the word

⇓

1

2

4

5

6

7

3

9

8

1 moving2 You can hear this.3 In a spring.4 In a circuit.5 From the Sun.6 stored7 Wasted energy often takes this

form.8 More at the top of the hill.9 In a battery.



I1 Plenaries

Review learning� Pupils look at the circuits shown and calculate the voltage for

each one.

Sharing responses� Each group of pupils prepares a sentence to say what they found

out about voltage by doing their experiment. Ask a spokesperson from each group to give their finding.

� Make a list of key points on the board to summarise.

Group feedback� Pupils work in groups, looking at circuit diagrams and deciding

where to draw the voltmeter to measure the voltage wanted.

� Pupils could work on paper or on whiteboards, copying the example circuit the teacher has drawn on the board and then adding the voltmeter.

Word game� Pupils take it in turns to describe an electrical component while

others decide what it is.

� Pupils could choose the component, or you could write some on cards and they could choose a card.

� Possible components are: lamp, connecting wire, battery, switch, fuse, motor, buzzer, heating wire, resistor, variable resistor, two-wayswitch or LED. Choose only those pupils have met, and rememberthat they may have come across some in other contexts, forexample capacitors in Design and Technology.

Looking ahead� Pupils look at some examples of different types of battery to see

what they are made of (NiCd, alkaline, lithium, lead acid). Tellthem that a chemical reaction produces electricity. Show some acidwith metal plates and connect a voltmeter to show the voltage.Point out the bubbles of gas forming as the metals react with theacid.

➔ Pupil sheet

Answers1A 3 V; 1B 1.5 V; 1C 3 V;1D 4 V; 2A 1 V; 2B 3 V; 2C 7 V.

➔ Teacher sheet

EquipmentExamples of batteries: e.g.alkaline, lithium; rechargeablebatteries: e.g. car battery (leadacid), nickel cadmium (NiCD)and metal hydride

Battery demonstration: a pieceof zinc and a piece of copper in aglass beaker of dilutehydrochloric acid, each piececonnected to one terminal of avoltmeter


Review learning

Calculate voltage fordifferent combinationsof batteries andcomponents.

Sharing responses

Each group prepares asentence to say what theyfound out about voltage inActivity I2a or I2b.

Group feedback

Given circuitdiagrams, pupils drawin the voltmeter inthe correct position.

Word game

What am I? Pupilsdescribe a componentwhile other pupilsguess what it is.

Looking ahead

Look at some batteries to see what they aremade of. Show a battery demonstration:metal plates in acid producing a voltage.Leads into I2 Investigate.

I2 Energy in and out


I2 PlenariesEnergy in and out

Review learning

What will the voltage reading be on each of these voltmeters?

1 Each cell has a voltage of 1.5 V and all the lamps are exactlythe same.

2 These cells are all different.


A

C

B

D

0.5 V

V

V

M

V

V

V

?

? ?

?

A B

VV

M

8 V

12 V

1V

1V

2V

9 V ?

?

C

? 4V

M

V

V

M

V V V

V V

V

V

V

M


I2 PlenariesEnergy in and out


Group feedbackTeacher sheetUsing individual whiteboards will give pupils the opportunity to practisedrawing circuit diagrams and to change their mind about where to place thevoltmeter. Pupils can work alone, in pairs or in small groups.

1 Draw the circuit on the board.(Draw the voltmeter symbol if you feel the group needs reminding of it. You may also want to remind them that the voltmeter isconnected across a component; this will depend on the pupils.)

2 Ask pupils to draw in a voltmeter which would measure thebattery voltage.

3 Ask them to hold up their whiteboard to show you.

Possible solutions:

4 Select correct solutions which are different and ask pupils to show them to the whole class.

5 Ask pupils to draw a voltmeter to measure the voltage across lamp A.

Possible solutions:

6 Ask pupils to draw a voltmeter to measure the voltage acrosslamp B.

Possible solutions:

A B

V

V

VV

A B

V

V

A B

V

V

Lamps A and B

A B

A

B

CV V

Lamp C

A

B

C

V

V

Possible solutions are:

Battery

A

B

C

Other circuits can be used, forexample:

A

B

C

V

V V



I2 PlenariesInvestigate: How to increase thevoltage in a fruit cell

Review learning� Pupils look at their graph and check if they have

correctly plotted the points. (This is important if theconclusions are to make sense. If the origin is includedthere should be a steep rise to the 0.5 cm point.) There isa best-fit straight line between 0.5 cm and 2.0 cm. Noinformation is given after this point.

� Pupils look at the suggested conclusions. Discuss withthem whether each one fits the data and the graphplotted.

� Finally, ask them to suggest which parts of the suggestedconclusions they can put together to make an accurateconclusion from their graph.

Group feedback� Pupils discuss the results of their experiment in groups.

� Pupils write a conclusion about the pairs of metals andthe voltage produced. They should also outline aproblem they encountered, and an improvement theywould make if doing the experiment again.

Analysing� Pupils give their results for different pairs of metals. If

each group gives the lowest voltage pair and the highestvoltage pair you may be able to draw up a list on theboard.

� Ask if you could put all the results together. The answer is‘no’ – because of other variables, the voltages will not becomparable, but it may be possible to create a list ofhighest to lowest pairs.

Evaluating� Allow pupils some time to discuss problems they

encountered in Activity I2d and to pick one to share with the class.

� Ask each group to give their problem and discuss with the class whether this invalidates results. After class discussion ask each group to come up with oneimprovement they could make. If there is time, discussthe improvements with the class.

➔ Pupil sheet

Answers1a–c Do not match shape of graph; d OKbut vague; e Not true between 0 and 0.5 cm; f Clear and specific description.

2 Voltage goes up quickly to 1.25 V for thefirst 0.5 cm of copper, then in steps of 0.06 V for each 0.5 cm of copper until thelength of copper in the lemon reaches 2.0 cm.


Review learning

Pupils use a list of possibleconclusions for Activity I2e anddiscuss whether the data supportsthem. Use the list to produce afinal conclusion.

Group feedback

Pupils discuss their conclusions toActivity I2d in groups.

Analysing

Look at results from differentgroups for Activity I2d. Discuss towhat extent the results wererepeated, and whether all resultscould be collected together (‘no’ ifvariables different).

Evaluating

Ask each group to give one problemthat they encountered in ActivityI2d and one improvement theycould make.


I2 PlenariesInvestigate: How to increase thevoltage in a fruit cell

Review learning

1 How well do these conclusions fit the graph you have plotted?

a The voltage goes up quickly at first but then in smaller andsmaller steps until it doesn’t change at all.

b The voltage goes up very quickly to a constant value, butsmall errors mean that the voltage readings change a littleeach time the copper is pushed in.

c The voltage goes up quickly to 1.25 V for the first 0.5 cmof copper and then doesn’t change much.

d Between 0.5 cm and 2.0 cm the voltage goes up steadily.

e The voltage goes up in even steps of about 0.06 V for each0.5 cm of copper.

f Between 0.5 cm and 2.0 cm the voltage goes up in evensteps of about 0.06 V for each 0.5 cm of copper.

2 Choose correct bits from all of these conclusions to produceone that fits your graph as closely as possible.




I3 PlenariesUsing electricity

Review learning� Draw up a large table on the board with columns for

‘electrical appliance’, ‘high energy user’, ‘low energyuser’, and ‘efficient’.

� Pupils think of examples of electrical appliances andsuggest them.

� All pupils decide which columns to tick.

� Examples: kettle = high energy user; tungsten light bulb =low energy user but not efficient; fluorescent tube = low energy user and efficient.

� Be prepared to write ‘some’ in the efficient column, forexample some fridges are designed to be more efficientthan others.

Sharing responses� Pupils work in groups, maybe using whiteboards, to

re-order the list of appliances and running times on thesheet from high energy to low energy.

Group feedback� Pupils discuss their results from Activity I3a. Consider

what the appliances that use the most energy have incommon. (They produce a lot of heat.)

� Pupils compare the tungsten light bulb and low-energyfluorescent bulb. Where does the extra energy go in thetungsten bulb? (heat)

Word game� Pupils play a game of hangman. This is a whole-class

activity. If a pupil guesses the word, get them to comeand do the next one for the class.

� Choose words like: conserved, dissipated, efficiency,transfer, kilowatt hour.

Looking ahead� Pupils think about where the electricity in the home

comes from.

� Pupils make a list of all the types of power station andways of generating electricity that they can think of.

➔ Pupil sheet

Equipmentcalculators

Answers5, 1, 4, 2, 3

Answerscoal, oil and gas, biomass (e.g. willow,chicken manure), wind turbines,hydroelectric, geothermal, wave turbines,tidal, nuclear, solar


Review learning

Build up a table ofelectrical appliances on theboard (high energy user, orlow energy user, and is itefficient?).

Sharing responses

Pupils work in groups toorder a list of appliancesand running times fromhigh energy to low energy.

Group feedback

Discuss results forelectrical appliancesfrom Activity I3a.

Word game

Pupils play a game ofhangman with words likeefficiency, conserved,dissipated.

Looking ahead

Pupils think about where electricalenergy for the home comes from. Howmany different types of powerstation/generator can they rememberfrom Year 7?


I3 PlenariesUsing electricity

Sharing responses

Put these energy uses in order from highest energy use to lowest.

1 100 W light bulb for 5 hours.2 750 W microwave oven for 10 minutes.3 33 W hair straightener for 20 minutes.4 3 kW kettle for 5 minutes.5 3 kW fan heater for 1 hour.

Remember

1 kW = 1000 W1 minute = 60 seconds1 hour = 3600 seconds.


Sheet 1 of 1

PlenariesI3 Using electricity

Sharing responses

Put these energy uses in order from highest energy use to lowest.

1 100 W light bulb for 5 hours.2 750 W microwave oven for 10 minutes.3 33 W hair straightener for 20 minutes.4 3 kW kettle for 5 minutes.5 3 kW fan heater for 1 hour.

Remember

1 kW = 1000 W1 minute = 60 seconds1 hour = 3600 seconds.




I4 PlenariesPower stations

Review learning� Pupils watch a demonstration of the model steam engine

(e.g. Mamod) if available.

� Pupils are asked to name different parts and say whatthey are for. (Furnace burns fuel, boiler heats water togive steam, steam turns turbine, turbine turns generator,generator produces electricity, electricity lights lamp.)

Sharing responses� Pupils order cards to show power station processes and

energy changes.

� Pupils work in groups to assemble the cards in order.

Group feedback� Pupils sort comments about power stations into three

lists: ‘for’, ‘against’ and ‘neutral’. These includeenvironmental concerns and the need to have reliablepower.

Word game� Give each pupil a card with a question and an answer on

it. Ask one pupil to stand up and read out just thequestion on their card, then sit down. The pupil who hasan appropriate answer to this question stands up, readsout their answer, then asks the question on their cardand sits down, and so on.

� The game is complete when the pupil who started thegame stands up for the second time to read out theanswer on their card. The loop is complete.

� If there are not enough question/answer cards for thewhole class, you may need to make extra copies. Somepupils will have the same question/answer card – the firstone to stand up gets to read their answer and ask theirquestion.

Looking back� Pupils revise and consolidate knowledge from the unit.

They can use the Unit map, Pupil checklist, or the Testyourself questions.

➔ Teacher sheet

➔ Pupil sheet

AnswersP4 (E3), P1 (E6), P6 (E5), P3 (E1 or E2), P5 (E1 or E2), P2 (E4)

➔ Pupil sheet

AnswersFor: 3, 8, 9; Against: 1, 4, 5, 10, 11;Neutral: 2, 6, 7, 12. (Discussion point: 6does not say that renewable is good, butpeople who take that for fact may say thisis a point ‘for’ rather than ‘neutral’.)

➔ Teacher sheet

➔ Unit map

➔ Pupil checklist

➔ Test yourself


Review learning

Show a model steam engineand talk about the differentparts in relation to a powerstation.

Sharing responses

Pupils order cards to recappower station and energychanges, as used in ActivityI4a.

Group feedback

Pupils sort comments aboutpower stations into ‘for’,‘against’ and ‘neutral’.

Word game

Loop game on whole unit tocheck progress.

Looking back

Pupils revise andconsolidate knowledge fromthe unit.


I4 Plenaries


Power stations

Review learningTeacher sheetEquipment

Use the following for a teacher demonstration:

� model steam engine which runs on tablet fuel (e.g. Mamod)� tablet fuel� tap water will do but distilled water is better if available

Running the activity

� Try out the steam engine before the lesson and test the safety valve.� Use hot water in the boiler to save time.� Hexamine-based tablet fuel burns well, does not give off toxic fumes and is

wax coated to prevent spitting.

Safety

� Do not use a model steam engine that runs on liquid fuel. Use solid fueltablets and avoid skin contact.

� Check the safety valve moves freely before each use.� Staff should be shown how to use the steam engine by an experienced

colleague.



Sharing responses

1 Discuss with your partner the correct order for the power station cardsand set them out in a line.

2 Discuss which energy card gives the correct energy or energy transferfor each of the power station cards and place them underneath:


Firstpowerstationcard

Nextpowerstationcard

First energyor energytransfer

card

Next energyor energy

transfer card

Power station cards Energy and energy transfer cards

P1 Coal burns in furnace. E1 kinetic energy

P2 Generators produce electricity in wires.

E2 kinetic energy

P3 Steam turns turbines. E3 chemical energy

P4 Furnace filled with coal.E4 kinetic energy →

electrical energy

P5 Turbines turn generators.E5 thermal energy →

kinetic energy

P6 Water is heated to steam in the boiler.

E6 chemical energy →thermal energy



Group feedback

Sort the statements into three lists:

For: The statement supports the type of power station.Against: The statement is against the type of power station.Neutral: The statement is neither for nor against any particular type of power station.


For Against Neutral

1 Wind turbines spoil the view of thelandscape.

2 Coal-fired powerstations can be foundnear large rivers aswater is needed forthe cooling towers.

3 Nuclear powerdoesn’t producesmoke and fumes.

4 Coal-fired powerstations contribute toglobal warming.

5 Nuclear waste is veryradioactive and willnot be safe for years.

6 Wind turbines userenewable energy.

7 Hydroelectric powercan be used inmountainous regions.

8 Solar panels produceelectricity in daylight – it doesn’t have to besunny.

9 Gas-fired powerstations can beswitched on and offquickly (compared tosome others).

10 We should notdepend on fossil fuelsbecause one day theywill run out.

11 Some hydroelectricdams have createdlakes where therewere farms andvillages.

12 Groups of windturbines have beenbuilt in the sea.



Word gameTeacher sheetQuestions and answers for a loop game.

Sheet 1 of 2 © Harcourt Education Ltd 2004 Catalyst 3This worksheet may have been altered from the original on the CD-ROM.

Q

How do you connecta voltmeter in acircuit?

Q

What is electriccurrent measured in?

Q

What are the energychanges in a torch?

Q

Which part of apower station turnsthe kinetic energy toelectrical energy?

Q

What types of energycan be stored?

Q

Which uses mostenergy, a 100 W bulb for 1 hour or a 70 W television for3 hours?

Q

What type ofelectrical appliancesin the home use most energy per hour?

Q

Where does lightenergy from a torchend up?

A

Energy cannotbe made ordestroyed.

A

Amps (A)

A

The generator.

A

The television.

A

The energy isabsorbed by theparticles thelight hits. It isspread about(dissipated).

A

chemical →electrical →light andthermal

A

Across thecomponent orbattery.

A

Chemical,gravitationaland strainenergy.


I4 PlenariesPower stations (continued)


Q

Three renewable types of energy are:

Q

What word describeswashing machinesthat use less energythan other washingmachines?

Q

What is electricalenergy measured in?

Q

What fuels are fossilfuels?

Q

How can we reducethe amount ofthermal energyescaping from ourhomes?

Q

How many 1.5 Vbatteries are neededto supply 9 V?

Q

What doesconservation ofenergy mean?

A

Applianceswhich heatthings, like fanheaters orkettles.

A

efficient

A

Coal, oil andgas.

A

Six batteries.

A

Joules orkilowatt hours.

A

Wind,hydroelectricand solar.

A

Insulate them.


I1 SpecialsMake it work

1 All of these devices use electrical energy.

Draw lines to match the device to the energy it releases.

2 Draw lines to match the device to its energy transfer diagram.


heat

sound

movement

toaster

radio

lamp

motor

light

electrical energy → light energy +sound energy

electrical energy → heat energy

electrical energy → sound energy



12 34 5 67

8 90 #

*

ROC

K

PLAYCLASSIC

BASS

PO

TRACK

SELECTSTART

B R

mobile phone

television

mp3 musicplayer

computer game

iron

I-Specials.qxd 08-Jun-04 5:29 PM Page 1

I1 SpecialsMake it work (continued)

3 Look at this list of words.

a Colour in red the ways energy can be transferred.

b Colour in blue the ways energy can be stored.

4 Look at these statements about energy.

a Colour the true statements in green.

b Cross out the false statements.


sound

movement

light

electrical

heatstrain

chemical

gravitational

Energy cannot be stored.

Energy can be made.

Energy can be stored.

Energy cannot be made.

Energy can move from place to place. It can be transferred.

Energy cannot move from place to place. It cannot be transferred.


1 Draw lines to match the words and symbols to the descriptions.

2 Look at these circuit diagrams.

Write the letter A, B or C to show the correct answers.

a A voltmeter is connected wrongly in circuit .

b The voltage is being measured across abuzzer in circuit .

c The voltage is being measured across a cell in circuit .

3 Look at these circuit diagrams.

a Complete this table by writing in the voltage for each circuit.

b Underline the correct word to complete the sentence.The more batteries there are in a circuit, the(smaller/higher/bigger/lower) the voltage.

I2 SpecialsEnergy in and out


V

B

C

V

A

V V

voltage

volts

V

Voltage is measured in this unit.

The circuit symbol for a voltmeter.

The symbol for volts.

This tells us where there is a change inenergy in an electrical circuit.

V

C

5

43210 v

V

B

5

43210 v

V

A

5

43210 v

Circuit Number of batteries Voltage in V

A 1

B 2

C 3


I3 SpecialsUsing electricity

1 Write true or false for each sentence.

a The lower the voltage, the more energy that can be transferred.

b Different devices transfer different amounts of energy.

c When energy dissipates it is wasted.

d Saving energy makes my electricity bill more expensive.

e Saving energy costs me more money.

f We should save energy because our energy resources won’t last forever.

2 Look at these diagrams of two light bulbs. The light energy is useful.The heat energy is wasted.

a Which bulb wastes most energy?

b Energy costs money. Which is the cheaper bulb to use?


A B5 J light energyper second

5 J light energyper second

35 J heat energyper second

12 J heat energyper second


I3 SpecialsUsing electricity (continued)

3 Look at this list of things you could do that useenergy.

a Colour in green the ways to save energy.

b Colour in red the ways to waste energy.


Turn lights off when they’re not needed.

Insulate your home to keep the heat in.

Hang out the washing to dry.

Use 100 W bulbs instead of 60 W bulbs.

Use low-energy bulbs in lights.

Wash clothes at a higher temperature.

Use the oven to heat up food rather than the microwave.

Use the tumble drier to dry clothes.

Turn the central heating up.

Wash clothes at a lower temperature.

Use 60 W bulbs instead of 100 W bulbs.

Keep your home draughty.

Buy energy efficient devices.

Use the microwave for heating up food rather than the oven.


1 Use these words to fill in the gaps.

a You need to make things work.

b Energy is never used up. It is always .

c An energy source that can be replaced is .

d An energy source that is used up faster than it can be replaced is.

e A transfers kinetic energy to a generator.

f The more a device is, the less energy it wastes.

g A turns kinetic energy into electrical energy.

h Energy that is spread out and wasted is .

2 Look at these pictures of energy sources.

a Colour in greenthe pictures ofrenewable energysources.

b Colour in redthe pictures of non-renewableenergy sources.

3 Turbines need to beturned by something.Look at this list. Draw a circle around the things that can turn a turbine.

I4 SpecialsPower stations


conserved energy generator

renewable

dissipated

non-renewableturbine efficient

wood

oil

coalwind generator

oil

solar panel

petrolnatural gas

hydroelectricpower station

sunshine

wind

coalsteam

falling wateroilwaves


I Specials answersEnergy and electricity

I1 Make it work

1 toaster – heatmotor – movementradio – soundlamp – light

2 mobile phone – electrical energy →sound energy

mp3 music player – electrical energy →sound energy

television – electrical energy → light energy + sound energy

computer game – electrical energy →light energy + sound energy

iron – electrical energy → heat energy3 a Coloured red – heat, sound, movement, light,

electrical.b Coloured blue – gravitational, strain, chemical.

4 Coloured green – energy can move from place toplace. It can be transferred. Energy can bestored. Energy cannot be made.Coloured red – energy cannot be stored, energycannot move from place to place. It cannot betransferred. Energy can be made.

I2 Energy in and out1 voltage – This tells us where there is a change in

energy in an electrical circuit.volts – Voltage is measured in this unit.V – The symbol for volts.

– The circuit symbol for a voltmeter.

2 a Bb Cc D

3 a

b bigger

I3 Using electricity1 a false

b truec trued falsee falsef true

2 a Ab B

3 a Coloured green – Turn lights off when they’renot needed. Insulate your home to keep theheat in. Hang out the washing to dry. Washclothes at a lower temperature. Use lowenergy bulbs in lights. Use 60 W bulbsinstead of 100W bulbs. Buy energy efficientdevices. Use the microwave for heating upfood rather than the oven.

b Coloured red – Turn the central heating up.Use 100 W bulbs instead of 60W bulbs. Washclothes at a higher temperature. Use the ovento heat up food rather than the microwave.Use the tumble drier to dry clothes. Keepyour home draughty.

I4 Power stations1 a energy

b conservedc renewabled non-renewablee turbinef efficientg generatorh dissipated

2 a Coloured green – wood, wind generator,hydroelectric power, solar panel.

b Coloured red – coal, oil, natural gas, petrol.3 Circled – wind, steam, waves, falling water.

V


Circuit Number of Voltage (V)batteries

A 1 1.5

B 2 3.0

C 3 4.5

Spe Answers.qxd 6/23/2004 9:19 AM Page 9

I1 HomeworkMake it work


HELP

1 Rewrite the table to match the type of energy to its correctdescription.

2 Match the beginning of each sentence with the correct ending.Write out each complete sentence.

Beginnings Endings

A An electric drill transfers 1 into sound energy.electrical energy

B A diver diving off a diving board 2 into light energy and heat energy.transfers gravitational energy

C An electric fire transfers 3 into movement energy and sound electrical energy energy.

D A filament lamp transfers 4 mainly into heat energy.electrical energy

E A radio transfers electrical energy 5 into kinetic energy.

Type of Descriptionenergy

Thermal The energy transferred when an object moves.

Kinetic The energy transferred from a loudspeaker.

Chemical The energy stored in a coiled spring.

Strain The energy in very hot objects.

Sound The energy stored inside a cell or battery.

I-Homework.qxd 27-May-04 11:02 AM Page 1

I1 HomeworkMake it work (continued)

CORE

3 Scientists say that energy is conserved. In a television, electrical energy istransferred into light, heat and sound.

a Draw an energy transfer diagram to represent these energy transfers.

b Explain how energy is conserved when a TV is working.

c i Which part of the energy transfer is not really useful?

ii Use this idea to explain why a television is not a 100% efficientobject.

d i The electrical energy that is transferred in a TV comes from a powerstation. Where is the energy transferred from, to make the electricityin the power station?

ii Why is electricity from the mains supply more useful for powering aTV than electricity from a battery?

EXTENSION

4 DIY Dave is using his battery-powered drill. 1000 J of electrical energy gointo his drill. 800 J of kinetic energy and 120 J of sound energy aretransferred out of the drill. Pete the painter says that Dave’s drill is notconserving energy.

a Calculate the amount of energy that Pete thinks is missing.

b What has happened to this missing energy?

c Calculate the percentage of the energy that is transferred usefully.

d Dave’s other drill transfers 1500 J of energy into the drill. It transfers1200 J of kinetic energy and 150 J of sound energy out of the drill.Explain which of the two drills is the more energy-efficient. Show yourworking out.

5 Fridges in a shop now carry an energy efficiency sticker on the outside.Class A is very energy efficient, down to Class F, which is not very efficient.Jessica is choosing between two fridges. Electrobright has a Class E stickerand Fridgicold has a Class B sticker.

Explain which fridge is wasting the most energy and how it is being wasted.



I2 HomeworkEnergy in and out

HELP

1 a Match the beginning of each sentence with the correct ending. Write out each complete sentence.

b The objects in the boxes can all be found in electrical circuits.

Copy the headings below to make a table. Write each object into the correctcolumn to show how each object transfers energy in a circuit.

CORE

2 Look at the circuit diagrams. They have been set up to measure:

A the voltage across the bulb. C the voltage across the connecting wires.

B the voltage across the cell. D the voltage across the bulb.

There is a problem with each one. Explain what the problem is.


Beginning Ending

A The voltage measured across 1 shows that energy is being transferred a cell out of a circuit.

B The voltage measured across 2 shows that more energy is being a bulb transferred into the circuit by two cells.

C No voltage can be measured 3 shows that energy is being transferred across the wires in a circuit which into a circuit.

D The voltage measured across two 4 shows that no energy is being identical connected cells is larger transferred in the wires.than the voltage across only one cell which

buzzer motorbattery bell solar cell

Transfers energy into the circuit Transfers energy out of the circuit

A

V V

B C D

V

V


I2 HomeworkEnergy in and out (continued)

3 Look at the circuit diagrams below. The bulbs in each circuit areidentical. The 1.5 V cells are also identical.

a What is the voltage across

i cell A? ii cell B? iii cell C?

b Which bulb transfers the most energy out of the circuit?

c Which bulb will be the least bright?

d All three circuits are switched on and left. Which circuit willtransfer all the available energy out through the bulb first?

EXTENSION

4 Jim wants to use a solar cell to power the fan on his desk in thesummer. He sets up a circuit containing the solar cell, a fan andconnecting wires. He wants to find out if all the energy from thesolar cell is being converted into movement of his fan.

a How would Jim connect a voltmeter to measure:

i the voltage transferred into the circuit?

ii the voltage transferred out of the circuit?

b Jim works out the amount of kinetic energy transferred intothe fan. It is less than the energy transferred into the circuit.

Explain what has happened to the rest of the energy.

c Jim swaps his fan for one with a much heavier fan blade.

i How will this affect the speed of the fan?

ii Explain why changing the fan will have this effect.

iii What must Jim do to make the larger fan run at the samespeed as the smaller one?


CBA


I3 HomeworkUsing electricity

HELP

1 The table shows the amount of energy transferred every secondby several electrical devices.

a Write a list of the devices in order of the amount of energytransferred. Start with the one that transfers the mostelectrical energy every second.

b Which device will be the most expensive to run for oneminute?

c John has an electric shaver. It runs on a voltage of 230 V. He goes on holiday abroad. The voltage there is 110 V. Why does his shaver run very slowly?

CORE

2 Tamsyn has a tumble dryer in her garage. It has two heatsettings, marked “High” and “Low”.

a Why will the dryer cost Tamsyn less if she runs it for 1 houron the low setting instead of for 1 hour on the high setting?

b Why might her clothes still be wet, on the low setting?

c The tumble dryer has a grade B for energy efficiency. A cheaper model has a grade E for energy efficiency. Explain why Tamsyn’s model is good for the environment.

d Why are no tumble dryers 100% energy efficient?

e Why is it important that the tumble dryer’s plug has aproperly connected earth wire?


Electrical device Energy transferred per second (J)

A 40 W light bulb 40

B Electric kettle 1250

C Alarm clock 20

D Computer 350

E Tumble dryer 6000

F Electric drill 950


I3 HomeworkUsing electricity (continued)

f The energy consumption of Tamsyn’s dryer is 6000 joules persecond on the high setting and 4000 joules per second onthe low setting.

i How much energy will the dryer transfer per minute onthe low setting?

ii How many times more energy will it consume, perminute, on the high setting? Show your working out.

g Tamsyn notices that, when the tumble dryer is working, hergarage seems warmer. Explain why this happens.

EXTENSION

3 Patti has just had some solar panels fitted into the roof of herhouse. She will use them to heat the water in her hot watercylinder.

a What type of energy resource will the solar panels be using?

b How is this type of energy resource different from the gasboiler she used to use?

c The solar panels were fairly expensive to buy and fit but Pattiis sure she will be saving money after a couple of years.Explain why she will eventually save money.

4 The table gives some data about the energy transfers in ahairdryer.

a Draw a Sankey diagram to represent the energy changes in ahairdryer.

b What type of energy has not been labelled in the table?

c How does the data support the idea of conservation ofenergy?


Type of energy Amount transferred (kJ)

Electrical energy 100

Heat energy 80

Kinetic energy 17

3


I4 HomeworkPower stations

HELP

1 The pictures show several different ways that can be used togenerate electricity.

a Make a list of the energy resources that don’t use fossil fuels.

b Which two energy resources only work when the weather isright for them?

c Which energy resource depends upon falling water?


A

D

B

E

G H

C

F


I4 HomeworkPower stations (continued)

CORE

2 Look again at the diagrams for question 1.

a Which energy resources might cause global warming?

b Which energy resource would produce carbon dioxide but is not a fossil fuel?

c The labels below show types of energy and parts of a power station used to produce electricity from natural gas. Put them in the correct order in which you would meet them in the power station, starting from the natural gas.

d Draw an energy transfer diagram for a power station that uses falling water.

EXTENSION

3 Many parts of the world rely on biomass to generate electricity.

a Explain what is meant by the word “biomass”.

b Explain why biomass is a renewable energy source.

c Give one disadvantage of using biomass in a power station.

d Where did the energy in biomass originally come from?

4 There are many sources of energy that can be used to generate electricity. The labels below show where their energy might come from.

For each of the following energy sources say where its energy comes from. Use the letters.

a Natural gas b Wave power c Nuclear d Solar


A – From the Sun but not directly.

B – From somewhere other than the Sun.

C – Straight from the Sun.

A turbine

D burning E kinetic energy in steam

B electrical energy C generator

F chemical energy in gas


I1Homework

mark schemeMake it work


HELPQuestion Answer Mark

1 Thermal – the energy in very hot objects. Kinetic – the energy transferred when an object moves. Chemical – the energy stored inside a cell or battery. Strain – the energy stored in a coiled spring. Sound – the energy transferred from a loudspeaker. 4 Award 4 marks for 4 or 5 correct, 3 marks for 3 correct to 1 mark for 1 correct.

2 A – 3; B – 5; C – 4; D – 2; E – 1 4Award 4 marks for 4 or 5 correct, 3 marks for 3 correct to 1 mark for 1 correct.

Total for Help 8

COREQuestion Answer Mark

3 a

3

Maximum of 3 marks. Deduct 1 mark for each error.

b The amount of energy transferred into the TV is equal to 1the total amount of energy transferred out of the TV. 1

c i The heat/thermal energy. 1

ii Not all of the available electrical energy is transferred as sound and light. Some of the electrical energy is wasted as heat. 1

d i From coal/oil/natural gas. Accept any alternative energy source. 1

ii Mains electricity does not run out as a battery does. 1The battery would not need replacing if it runs on mains electricity. 1Accept sensible alternatives.

Total for Core 10

EXTENSIONQuestion Answer Mark

4 a 1000 – 920 = 80 J 21 mark for the value + 1 mark for the unit

b It has been dissipated/lost to the atmosphere as heat. 1

c 920/1 000 × 100 = 92% 1

d 1350/1500 × 100 = 96.1% Accept 96.0% 1So this drill transfers a higher percentage of energy usefully/is more efficient. 1

5 Electrobright is wasting the most energy 1as heat that is dissipated/given out to the atmosphere. 1

Total for Extension 8

electrical energyin TV

sound

light

heat


I2Homework

mark schemeEnergy in and out



1 a A – 3; B – 1; C – 4; D – 2 33 or 4 correct = 3 marks; 2 correct = 2 marks; 1 correct = 1 mark.

b Transfers energy into the circuit: battery; solar cell. Transfers energy out of the circuit: buzzer; bell; motor. 51 mark for each correctly placed item.

Total for Help 8


2 a The voltmeter is not connected to each side/across the bulb/the voltmeter is in series/not in parallel. 1

b The voltmeter is across the bulb not the cell/is measuring the energy transferred out of the circuit. 1

c The voltmeter is across the cell/is measuring the energy transferred into the circuit. 1

d The voltmeter is measuring the voltage across the wires/is not connected across the cell. 1Accept equivalent responses for all four questions.

3 a i 1.5 V 1

ii 3 V 1

ii 6 V 1

b Bulb in circuit C. 1

c Bulb in circuit A. 1

d Circuit A. 1

Total for Core 10


4 a i Connect the voltmeter either side of/across the solar cell. 1

ii Connect the voltmeter either side of/across the fan. 1

b It has been transferred into sound/heat/been dissipated. 1

c i The fan will run more slowly. 1

ii The heavier fan requires more energy to turn it at the same speed 1but the solar cell supplies a fixed amount of energy 1so the fan must slow down. 1

iii Use a more powerful solar cell. 1



I3Homework

mark schemeUsing electricity



1 a E > B > F > D > A > C. 5Award 1 mark for each of the following correct: E somewhere before B, B somewhere before F, F somewhere before D, D somewhere before A, A somewhere before C.

b The tumble dryer. 1

c There is less energy in the electricity (than at home) 1so the shaver transfers less per second and runs more slowly. 1Accept other equivalent responses.

Total for Help 8


2 a It transfers less energy on the low setting. 1

b There may not be enough heat transferred to dry the clothes. 1

c It wastes less of the electrical energy that goes into it. 1

d Some energy is always dissipated/lost as heat to the atmosphere. 1

e So that there is less chance of an electric shock. 1

f i 240 000 J or 240 kJ. 1

ii 6000/4000 or 600 000/40 000 1=1.5 times more. 1

g Some of the energy transferred as heat escapes into the surroundings 1so the temperature of the air in the garage rises. 1

Total for Core 10


3 a A renewable energy resource. 1

b Gas is a non-renewable energy resource/gas cannot be replaced quickly. 1Do not give credit for responses that refer to re-use of the energy source.

c She will pay for less gas/she will use less gas/her gas bill will reduce. 1Sunlight is free. 1Accept reasonable alternative responses.

4 a Award 2 marks for a reasonably accurate Sankey diagram. 2Deduct 1 mark for a small error.

b Sound energy. 1

c The total energy input is equal to the total energy output. 1



I4Homework

mark schemePower stations



1 a B – windmill; C – hydroelectric; E – tree; G – Sun; H – nuclear. 5Award 1 mark for each correct response. Deduct 1 mark for each incorrect response in excess of five sources.

b B – windmill and G – the Sun. 2

c C – hydroelectric. 1

Total for Help 8


2 a A – coal; D – oil; E – tree; F – gas. All four needed for the mark. 1

b E – tree. 1

c Order is: E, D, A, C, B. 5F somewhere before D; D somewhere before E; E somewhere before A;A somewhere before C; C somewhere before B.

d potential energy in water kinetic energy in water kinetic energy in turbine or generator electricity 3Deduct 1 mark for each error.

Total for Core 10


3 a Material from living things/plant material. 1

b It is widely available/it can be quickly or easily replaced/you can grow more of it. 1Do not credit responses referring to using it again.

c It produces pollution/greenhouse gases/carbon dioxide or it leads to global warming. 1

d The Sun/sunlight. 1Responses must refer to the Sun.

4 a A – from the Sun but not directly. 1

b A – from the Sun but not directly. 1

c B – from somewhere other than the Sun. 1

d C – straight from the Sun. 1



I Test yourselfEnergy and electricity

1 Energy is transformed when mechanical toys, candles, turbines and water wheels are used. Complete the energy transformations for each of them.

a a wind-up toy:

energy →energy

b a candle:

→ and energyenergy

c a wind turbine:

energy → energy

d a water wheel:

energy →energy

2 All the bulbs in the circuits are the same.

a Write down the reading on each voltmeter.

P R

Q S

b Complete this sentence by crossing out the words that are wrong.

The bulbs in the series circuit will be brighter/less brightthan the bulbs in the parallel circuit because they are transforming more/less electrical energy to light energy.


V3 V

VQ

VP

V

V

3 V

R

SV

Test-Qust.qxd 6/25/2004 10:32 AM Page 24

I Test yourselfEnergy and electricity (continued)

3 Which of the appliances will use the most electricity in an hour? Circle the letter showing the correct answer.

A a 3 kW electric fire

B a 1 kW kettle

C a 60 W lamp

D a 500 W hairdryer.

4 Look at the diagram of a model for describing an electric circuit.

In this model, say what represents each of the following components:

the cell

the current

voltage

energy

a component

a switch

wires


1beanbag 3

beanbags

2beanbags


I Test yourselfEnergy and electricity (continued)

5 The diagram shows a gas-fired power station.

Complete the sentences below to explain how it works.

In a gas-fired power station, is burned to heat water

in the boilers and turn it into . This turns the turbines.

The turn the generators. The is

condensed in the . The waste

gases leave through the .

6 The two light bulbs both give out the same amount of light.

a Which bulb uses more electrical energy in one

minute?

b What happens to the electrical energy that is nottransformed into light?

c Which bulb will get hotter while it is being used?

d Explain your answer to c.

7 Anna says: ‘In all the transformations we have seen, energy is conserved – it is neither created nor destroyed.’

Explain how this can be true if two light bulbs give out the same amount of light while one uses more electrical energy than the other.


60 W conventionallight bulb

18 W energy-efficient light bulb

BA

coolingtowergenerator

turbineboiler

fuel


ITest yourself

AnswersEnergy and electricity

1 Energy is transformed when mechanical toys, candles, turbines and water wheels are used. Complete the energy transformations for each of them.

a a wind-up toy:

energy →energy

b a candle:

→ and energyenergy

c a wind turbine:

energy → energy

d a water wheel:

energy →energy

2 All the bulbs in the circuits are the same.

a Write down the reading on each voltmeter.

P R

Q S

b Complete this sentence by crossing out the words that are wrong.

The bulbs in the series circuit will be brighter/less brightthan the bulbs in the parallel circuit because they are transforming more/less electrical energy to light energy.

3 V1.5 V

3 V1.5 V

potential

kineticgravitational

electricalkinetic

lightheatchemical

potential

kineticelastic


V3 V

VQ

VP

V

V

3 V

R

SV

Test-Ans.qxd 16-Jun-04 2:55 PM Page 24

ITest yourself

AnswersEnergy and electricity (continued)

3 Which of the appliances will use the most electricity in an hour? Circle the letter showing the correct answer.

A a 3 kW electric fire

B a 1 kW kettle

C a 60 W lamp

D a 500 W hairdryer.

4 Look at the diagram of a model for describing an electric circuit.

In this model, say what represents each of the following components:

the cell

the current

voltage

energy

a component

a switch

wires circle on floor

gate

stepping stones or steps or wobble board

beanbags

the number of beanbags one child has

moving children

bin of beanbags


1beanbag 3

beanbags

2beanbags


ITest yourself

AnswersEnergy and electricity (continued)

5 The diagram shows a gas-fired power station.

Complete the sentences below to explain how it works.

In a gas-fired power station, is burned to heat water

in the boilers and turn it into . This turns the turbines.

The turn the generators. The is

condensed in the . The waste

gases leave through the .

6 The two light bulbs both give out the same amount of light.

a Which bulb uses more electrical energy in one

minute?

b What happens to the electrical energy that is nottransformed into light?

c Which bulb will get hotter while it is being used?

d Explain your answer to c.

7 Anna says: ‘In all the transformations we have seen, energy is conserved – it is neither created nor destroyed.’

Explain how this can be true if two light bulbs give out the same amount of light while one uses more electrical energy than the other.

The bulb using more electrical energy transforms more of it into heat.

More electrical energy is being transformed into heat in B.

B

It is transformed into heat.

B

chimney or flue

towerscooling

steamturbines

steam

gas


60 W conventionallight bulb

18 W energy-efficient light bulb

BA

coolingtowergenerator

turbineboiler

fuel


IEnd of unit test

GreenEnergy and electricity

1 Write the correct words for each space to complete thedescriptions of the energy transformations taking place.

a Electrical energy to energy. 1 mark

b Chemical energy to energy

2 marksand energy.

2 This diagram shows Dinorwig pumped storage power station.

Write the correct words for each space to complete the descriptionsof the energy transformations taking place.

a As water from the reservoir starts flowing down the pipes,

energy is transformed to energy. 2 marks

b This energy is then transformed to energy by the

generators. 1 mark

c During the process a lot of energy is wasted as energy. 1 mark

The pylons that carry the high voltage supply from the generators have a warning sign on them.

d Why is there a warning sign? 1 mark


powerstation

mountain

generatingpumpingpipes

reservoir

reservoir

G-I-EUTest.qxd 18-Jun-04 10:48 AM Page 16

3 a Write the correct words from the list below that are needed to complete the sentence. 1 mark

The bulb in the circuit transforms to light energy.

b Which beaker, A or B, could be used as a cell to light a bulb in a circuit? 1 mark

c Which of these statements describes what happens inside a cell to produce an electric voltage? 1 markA a change of stateB a temperature changeC a chemical changeD a physical change

d This table shows the voltage measured across differentcomponents in the same series circuit.

In one minute, which component transforms the most energy? 1 mark

IEnd of unit test

GreenEnergy and electricity (continued)


V

A

V = 0

samemetal

V

B

V = 1.1 V

differentmetals

Component Voltage measured (V)

bulb 1.3

buzzer 2.1

coloured bulb 0.9

heater 1.8

electric current electric voltage electrical energy


IEnd of unit test


4 This diagram shows a coal-fired power station.

a Using the diagram, describe what happens at stages A to D to produce electricity from coal. 4 marksThe descriptions for E to G are given below.E In the cooling towers steam condenses to water.F The hot waste gases rise out of the flue.G The pylons carry the electricity supply to the users.

b What problems might be caused by the flue gases? 1 mark

5 These bar charts show the electricity used by two different familiesA and B in one week.

a Which family uses more electricity in a week? 1 mark

b Give one way in which family A could be wasting energy. Use the bar chart to explain your answer. 2 marks


G

EA

F

BD

C

Uni

ts o

f ele

ctric

ity u

sed

in a

wee

k

heaters cooker lights

family A

iron kettle TV

Uni

ts o

f ele

ctric

ity u

sed

in a

wee

k


family B

iron kettle TV


IEnd of unit test


6 Andrew built this circuit. When he completed the circuit, the voltmeter read 1.5 V.

Andrew added a second, then a third cell. He added the results tohis table:

a Andrew added two more cells. Complete the table to show the rest of the results. 1 mark

b i What pattern could Andrew see in his results? 1 markii When Andrew added the sixth cell, the voltmeter

read 6 V, which did not fit the pattern. Suggest what Andrew had done with this cell in the circuit. 1 mark

Andrew used a different battery in the circuit. The voltmeter read 9 V.

c i Andrew says this proves the battery contains six cells. What evidence does he have to support this conclusion? 1 mark

ii Andrew wants some proof that he is right. He knows it would not be safe to cut open the battery. What would be the most reliable source of information to provide this proof? 1 mark


Number of cells Voltage (V)

1 1.5

2 3.0

3 4.5

4

5

6

V


IEnd of unit test

RedEnergy and electricity

1 This diagram shows a coal-fired power station.

a Using the diagram, describe what happens at stages A to D to produce electricity from coal. 4 marksThe descriptions for E to G are given below.E In the cooling towers steam condenses to water.F The hot waste gases rise out of the flue.G The pylons carry the electricity supply to the users.

b What problems might be caused by the flue gases? 1 mark

2 This diagram shows Dinorwig pumped storage power station.

Write the correct words for each space to complete thedescriptions.

a During the process a lot of energy is wasted asenergy. 1 mark

b Inside the generator (or dynamo) a moves to generate electricity. 1 mark


G

EA

F

BD

C

powerstation

mountain

generatingpumpingpipes

reservoir

reservoir


c When the demand for electricity is low, the spare electricityis used to pump water back up to the reservoir.

The electricity needed to pump all the water back upthe pipes is more than the amount of electricity generatedat first when the water flowed down the pipes.

Which statement correctly explains why this is? Write the letter. 1 mark

A Because some of the gravitational potential energy is used up when it is converted to electrical energy so the total amount of energy at the end is less than before.

B Because the amount of energy changes as it transforms to different types of energy.

C Because not all the gravitational potential energy is transformed to electrical energy and back to gravitational potential energy, although the total amount of energy is unchanged.

D Because the amount of energy present cannot be measured – the total amount is always changing.

d The pylons which carry the high voltage supply from thegenerators show this sign:

Describe a danger of the high voltage power lines. 1 mark

3 a Which of these statements describes what happensinside a cell to produce an electric voltage? 1 mark

A a change of stateB a temperature changeC a chemical changeD a physical change

b This table shows the voltage measured across differentcomponents in the same series circuit.

In one minute, which component transforms the most energy? 1 mark

IEnd of unit test

RedEnergy and electricity (continued)


Component Voltage measured (V)

bulb 1.3

buzzer 2.1

coloured bulb 0.9

heater 1.8


IEnd of unit test


4 These bar charts show the electricity used by two different familiesA and B in one week.

a Which family uses more electricity in a week? 1 mark

b Family A want to cut down their consumption of electricity.Give one way in which this family could be wasting energy. Use the bar chart to explain your answer. 2 marks

c Leanne uses a hairdryer rated at 500 W for half an hour a week. Electricity use is measured in kilowatt hours.

Calculate how many kilowatt hours Leanne uses for her hairdryer in a week. 1 mark

d Explain how the energy needed to keep a house warm can be reduced. 1 mark

5 This diagram shows a model used to explain electricity.


Uni

ts o

f ele

ctric

ity u

sed

in a

wee

k


family A

iron kettle TV

Uni

ts o

f ele

ctric

ity u

sed

in a

wee

k


family B

iron kettle TV

HOW TOCONSERVE

ENERGY

LOWER YOUR

HOUSEHOLD

HEATING BILLS

gerbiltrack

first hill

Gerbil Winding

Station

second hill, higher


a What represents the current in the circuit? 1 mark

b What represents the cell? 1 mark

c Which ‘component’ in this circuit transforms the most energy? 1 mark

d To increase the ‘voltage’ of the cell, what change would you make to the model? 1 mark

6 Andrew built this circuit. When he completed the circuit, the voltmeter read 1.5 V.

Andrew added a second, then four more cells. He added the results to his table:

Andrew used a different battery in the circuit. The voltmeter read 9 V.

a i Andrew says this proves the battery contains six cells. What evidence does he have to support this conclusion? 1 mark

ii Andrew wants some proof that he is right. He knows it wouldnot be safe to cut open the battery. What would be the most reliable source of information to provide this proof? 1 mark

iii The first time Andrew connected the battery, the voltmeter gave a minus reading. Suggest what Andrew had done to make the voltmeter do this. 1 mark

b i Andrew had a choice of an analogue or digital voltmeter to use. Hechose the digital voltmeter. Suggest his reason for choosing this meter. 1 mark

ii Andrew needed to be sure that his data from the experiment was reliable. What should he do to obtain reliable data? 1 mark

IEnd of unit test



V

Number of cells Voltage

1 1.5

2 3.0

3 4.5

4 6.0

5 7.5

6 9.0


IEnd of unit test

mark schemeEnergy and electricity


Green (NC Tier 3–6)Question Answer Mark Level

1 a Heat 1 3

b Heat 1 3

Light 1 4

2 a Gravitational potential. 1 4

Kinetic 1 4

b Electrical 1 4

c Heat or heat and sound. 1 5

d High voltages are dangerous or cause electric shock or cause a high current to flow through you or can kill. 1 4

3 a Electrical energy. 1 5

b B 1 4

c C or a chemical change. 1 6

d Buzzer 1 5

4 a A In the furnace (allow fire) coal is burned. 1 5

B In the boilers water is boiled or heated. 1 5

C The steam turns the turbine. 1 5

D The generators turn and make electricity. 1 5

b Acid rain or pollution or global warming or other sensible suggestion. 1 6

5 a Family A. 1 6

b Any one from: Heaters left on; House not insulated; Doors left open; Lights left on; Accept any sensible answer. 1 6

Because the heaters or lights bar is higher for family A thanfor family B. 1 6

6 a 6, 7.5, 9. 1 4

b i Each cell increased the voltage by 1.5 V. 1 5ii Cell was reversed. 1 5

c i Six cells give 9 V, the same as the battery. 1 6ii The website/literature from the manufacturer. 1 6

Scores in the range of: NC Level

4–6 3

7–11 4

12–16 5

17–25 6


IEnd of unit test

mark schemeEnergy and electricity


Red (NC Tier 5–7*)Question Answer Mark Level

1 a A In the furnace (allow fire) coal is burned. 1 5

B In the boilers water is boiled or heated. 1 5

C The steam turns the turbine. 1 5

D The generators turn and make electricity. 1 5

b Acid rain or pollution or global warming or other sensible suggestion. 1 6

2 a Heat or heat and sound. 1 5

b Magnet or magnetic field. 1 7

c C 1 7

d Any one from: 1 6Large currents can cause fire.Cause electric shock. (Accept suitable alternatives)

3 a C or a chemical change. 1 6

b Buzzer 1 5

4 a Family A 1 6

b Any one from: Heaters left on; House not insulated; Doors left 1 6open; Lights left on. Accept any sensible answer.

Because the heaters or lights bar is higher for family A 1 6than for family B.

c 0.25 kWh 1 7*

d Accept any sensible suggestion relating to insulation. 1 7

5 a Gerbils moving. 1 6

b Wind-up station. 1 7

c Highest hill. 1 7*

d Wind up gerbils more or give gerbils more energy. 1 7

6 a i 6 cells give 9 V, the same as the battery. 1 6ii The website/literature from the manufacturer. 1 6iii The battery connected in reverse. 1 6

b i The digital meter gives a more precise reading. 1 7ii He should repeat his measurements several times. 1 7

Scores in the range of: NC Level

6–10 5

11–15 6

16–18 7

19–25 7*


I Pupil checklistEnergy and electricity


Learning outcomes I can do I can do I need to this very this quite do more well well work on this

I can name types of energy.

I can name the units of energy.

I can describe energy transfers.

I can identify energy transfers.

I can name the three types of stored energy: gravitational, chemical and strain energy.

I can describe energy conservation.

I can describe how electrical energy is transferred around circuits and transformed in components.

I can describe how a battery has stored chemical energy which is transformed by a chemical change to electrical energy in a circuit.

I can name the units of voltage.

I can use a voltmeter.

I can use a model to describe an electric circuit.

I can describe how not all energy is usefully transformed and some is wasted.

I can use a joulemeter.

I can describe energy dissipation.

I can describe what is meant by efficiency.

I can carry out calculations of efficiency. (Red only)

I can describe the dangers and benefits of electricity.

I can describe how a power station works.

I can use energy flow diagrams to show energy transformations. (Red only)

I can plan and carry out an investigation to find out what affects the voltage of a fruit cell.

Pupil-Checklist.qxd 17-Jun-04 8:00 PM Page 9

I GlossaryEnergy and electricity


Word

conserved

dissipated

energy efficiency

generator

gravitationalpotential energy

potential difference R

power rating R

Sankey diagram R

turbine

voltmeter

Definition

Energy is conserved: it is not created or destroyed, but justpasses from place to place. We call this ‘conservation ofenergy’.

The energy stored because something is lifted up.

Spread about. Energy such as light or heat is dissipated froma source to the surroundings.

An instrument used to measure voltage.

Another term for voltage. It is the difference in potentialenergy between two points on an electric circuit. R

How many watts (joules per second) of energy an electricaldevice transfers. For example, a light bulb can have a powerrating of 60 watts. R

How much energy a device wastes. Something with lowenergy efficiency wastes lots of energy.

A diagram that shows the amount of energy beingtransferred. The widths of the lines show the amounts ofenergy. R

A device that takes in kinetic (movement) energy and turns itinto electrical energy.

A device for changing movement in one direction intospinning movement.

Glossary.qxd 18-Jun-04 11:33 AM Page 10

I Key wordsEnergy and electricity

conserved

dissipated

energy efficiency

generator

gravitational potentialenergy


power rating R

Sankey diagram R

turbine

voltmeter

Sheet 1 of 1

Sheet 1 of 1


Key wordsI Energy and electricity

conserved

dissipated

energy efficiency

generator

gravitational potentialenergy


power rating R

Sankey diagram R

turbine

voltmeter


Keywords.qxd 18-Jun-04 11:35 AM Page 9


I Book answersEnergy and electricity

I1 Make it workGreena Heat, movement, light and sound energy.b The electric motor is quieter, doesn’t need fuel

topping up and doesn’t pollute the atmosphere.c chemical energy → light energy + heat energyd Both candle and electric lamp give out heat and

light energy. The lamp gives out more lightenergy than does the candle.

1

2 a 750 Jb 15 Jc 735 Jd

3 Individual answers.

Red

a i Any one from: quieter, no pollution, doesn’tneed fuel topping up.

ii It can be located anywhere even where thereis no electricity supply.

bSpring tightly

wound

Spring unwound

Inpu

t kin

etic

ene

rgy

by

win

ding

up

– en

ergy

sto

red

in s

prin

g as

str

ain

ener

gy

Spring unwinds to produce

kinetic energy in the dynamo w

hich

produces electric current to light

the torch

Batteries' chemicals used up

Battery torch

Wind-up torch

Inpu

t ene

rgy

is

chem

ical

ene

rgy

in

new

bat

terie

s

Chem

ical energy is transferred

to electrical energy as the current

flows and lam

p lights

c Individual answers with appropriate reasons.d i 70 J every second.

ii 30%1 a

b

2 a 1750 Jb It warms the air in the room.c 250 J altogether of the energy you want.d All of the input energy must appear as

the total of all of the kinds of energy outputs.

e The energy dissipation is the thermal energygiven out by the TV.

3 Individual answers.

I2 Energy in and outGreena i The ski lift.

ii The flow of skiers.iii The ski run.

b i 2.35 Vii 2.35 V

iii 0 Vc There is no difference in energy at the ends of

each wire.d i two

ii threeiii

1 Voltage means the change in energy betweentwo points. Volts are the units of measurementfor voltage. V in a circle represent a voltmeter. V is an abbreviation for ‘volts’.

2 a Voltage is measured in volts.b Voltage is measured using a voltmeter.c The more the voltage the brighter the lamp.

electrical hairdryer

thermal energy

kinetic energy

sound energy

energy

turn key clock

spring wound

strain energy

kinetic energy, pendulum swings

kinetic energy, hands turn

sound energy, tick-tock

input chemical

and kinetic energy

electrical hairdryer

thermal energy

kinetic energy

sound energy

energy

mobile batteries electrical movement,phone energy sound and

heat energy

iron the mains electrical heat energyenergy

food the mains electrical movement mixer energy and sound

(or heat) energy

Book Answers.qxd 18-Jun-04 12:44 PM Page 23


I Book answersEnergy and electricity (continued)

Reda There is no difference in energy at the ends of

each wire.b Potential difference.1 a Where there is a difference of energy between

two points.b A voltmeter.c volts

2 a i The cell, putting energy into the circuit.ii The lamp, where the energy comes out of

the circuit.iii The current.iv The difference in energy or the potential

difference.v The amount of resistance.

3 There are two ski lifts to be taken up and threedownhill ski runs to come down.

4 The voltage is modelled by the height of the skilift. The higher the lift goes, the more voltagethere is. Greater voltage allows the skiers at thetop to have more energy. The flow of skiersshows the current. The more skiers, the greaterthe current. The total energy transferred is then given by the number of skiers comingdown the slope and how high the slope hasbeen made.

I3 Using electricityGreena The voltage isn’t large enough to supply the

energy needed to move the big heavy trains.b The microwave oven uses much less energy to

cook food than an electric oven.c The higher the temperature of the wash water,

the more energy has been used. So using a lowertemperature wash uses less energy.

1 A 50 V supply would not allow enough energyto be supplied to the larger householdappliances like washing machines, dryers andelectric cookers.

2 a Lights transfer about 100 J for each secondthey are on. So turning off lights when theyare not needed saves energy.

b If you put 60W bulbs where there were 100 W bulbs you would be saving 40 J foreach second for each bulb that was on.

c Using the air outside to dry your wash willsave the energy that you would otherwise usein the tumble dryer.

3 Using a more energy efficient washing machinewill make Helen’s mother’s electricity bill lesseach month. This saving will eventually makeup for the extra £65 she paid for the energyefficient machine. After a while the savings willbe even more than the difference in price thatshe paid for it.

Reda The voltage isn’t large enough to supply the

energy needed to move the big heavy trains.b The microwave oven uses much less energy to

cook food than an electric oven.1 a Lights transfer about 100 J for each second

they are on. So turning off lights when theyare not needed saves energy.

b If you put 60 W bulbs where there were 100 W bulbs you would be saving 40 J foreach second for each bulb that was on.

c Using the air outside to dry your wash willsave the energy that you would otherwise usein the tumble dryer.

d Running your dishwasher on the cool cyclewill not heat the water to as high atemperature as the normal cycle and willsave energy.

2 Using a more energy efficient washing machinewill make Helen’s mother’s electricity bill lesseach month. This saving will eventually makeup for the extra £65 she paid for the energyefficient machine. After a while the savings willbe even more than the difference in price thatshe paid for it.

3 a Insulating his house will keep the heat givenout by the storage heaters from escaping sothe house will stay warmer for a longer time.This will cause less energy to be supplied tothe storage heaters when the next heatingcycle comes on.

b By using less energy on the heating cycle, lesselectricity is produced at the power station.This will make less fossil fuel to be used atthe power station.

c By using less energy there will be lesspollution and less global warming which willhelp save the planet.

I4 Power stationsGreena Individual answers.b i Jim’s answer points out the least

environmental damage.ii Mary’s answer points to the greatest

environmental damage.c No. Leaving the problem to be solved to the last

minute when the fossil fuels run out will notwork. We have to prepare for the time whenthere are no more fossil fuels ahead of time andmake the necessary changes now that will allowenergy to be harnessed without fossil fuels.

1 Conserved – not used up, just transferred orstored.Dissipated – spread about to the surroundings.Efficiency – the fraction of the energy that endsup where you want it.



I Book answersEnergy and electricity (continued)

Energy – makes things work.Generator – changes kinetic energy intoelectrical energy.Non-renewable – being used up faster than itcan be replaced.Renewable – being replaced, usually by the Sun.Turbine – transfers kinetic energy to the generator.

2 Wind can be used as a renewable source ofenergy. Wind turbines are ugly to some people.Coal is a non-renewable source of energy, easyto use but pollutes the atmosphere.Solar energy is renewable. It does not pollute theenvironment. It is expensive to construct solar cellslarge enough to supply large amounts of power.Falling water is a renewable source of energy. It causes no pollution but does need large dams to be built which cause changes to theenvironment.

Reda Individual answers.

b Using hot water from cooling towers means that less energy has to be used to heat thehouses by the normal central heating. Using less energy will cause less fossil fuel to be used at the power station.

c 3 MJ1 Conserved – not used up, just transferred or

stored.Dissipated – spread about to the surroundings.Energy efficiency – the fraction of the energythat ends up where you want it.Generator – changes kinetic energy intoelectrical energy.Turbine – transfers kinetic energy to thegenerator.

2 a Individual answers.b Individual answers.c Individual answers.d Individual answers.e Individual answers.


I Energy and electricity Unit guide - Physicslocker...This unit builds on:work on electricity and...

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Transcript of I Energy and electricity Unit guide - Physicslocker...This unit builds on:work on electricity and...