addison wesley 6 science technology · 2 science & technology 6 get started electricity is...

&6A d d i s o n W e s l e y

Electricity

TechnologyScience

Steve Campbell

Douglas Hayhoe

Doug Herridge

Lionel Sandner

Jim Wiese

Beverley Williams

Ricki Wortzman

Energy and Control •

Electricity

Addison Wesley

Science & Technology 6

Toronto

Coordinating & Developmental Editors

Jenny ArmstrongLee GellerLynne Gulliver

Editors Researchers

Susan Berg Paulee KestinJackie Dulson Louise MacKenzieChristy Hayhoe Karen TaylorSarah Mawson Wendy Yano, Colborne Communications CentreMary ReeveKeltie Thomas

Consultants

Klaus Ritcher, formerly Edgewood P.S., Toronto District School BoardKatherine Shaw, Miller’s Grove School, Peel Board of EducationOtto Wevers, Cummer Valley Middle School, North York

Pearson Education Canada would like to thank the teachers and consultantswho reviewed and field-tested this material.

Design

Pronk&Associates

Copyright © 1999 Pearson Education Canada Inc., Toronto, Ontario

All rights reserved. This publication is protected by copyright, and permissionshould be obtained from the publisher prior to any prohibited reproduction,storage in a retrieval system, or transmission in any form or by any means,electronic, mechanical, photocopying, recording, or likewise. For informationregarding permission, write to the Permissions Department.

The information and activities presented in this book have been carefullyedited and reviewed. However, the publisher shall not be liable for anydamages resulting, in whole or part, from the reader’s use of this material.

Brand names that appear in photographs of products in this textbook areintended to provide students with a sense of the real-world applications ofscience and technology and are in no way intended to endorse specificproducts.

ISBN 0–201–61404–9

This book contains recycled product and is acid free.Printed and bound in Canada.

3 4 5 – TCP – 03 02

• how electricity is transformed into sound, light, andmotion

• how to design electrical devices to send coded messagesto a friend

• how to identify uses of electricity in your school, home,and community

3Electricity

Electricity. It’s all around you. It’s invisible. It can be used for manypurposes such as listening to music, finding your way down a darkpath, or talking to a relative in another part of Canada. You will participate in an electric adventure as you learn about electricity.

U n i t

Launch: Electricity Is Everywhere . . . 2

1: The Shocking Background toElectricity. . . . . . . . . . . . . . . . . . . . . 4

2: Characteristics of Electricity. . . . . . 6

3: Where Does Electricity Come From? . . . . . . . . . . . . . . . . 10

4: Light Up the Class. . . . . . . . . . . . . 15

5: Key Features of Electrical Circuits . . . . . . . . . . . . . 17

6: Different Needs, Different Circuits . . . . . . . . . . . . . . 20

7: Fixing Electrical Problems . . . . . . 23

8: A Special Kind of Electricity – Static Electricity . . . . . . . . . . . . . . 26

9: Learning About Magnets . . . . . . . 28

10: Electrical Picker Uppers . . . . . . . 30

11: Talking Around the World –Thanks to Canadians . . . . . . . . . 32

12: Electricity – Use it Carefully . . . . 35

13: Conserving Electricity . . . . . . . . . 37

Design Project: Secret Talk . . . . . . . . 38

Unit Review . . . . . . . . . . . . . . . . . . . . 40

Glossary . . . . . . . . . . . . . . . . . . . . . . . 44

Now you will find out:

2 SCIENCE & TECHNOLOGY 6

Get StartedElectricity is everywhere! It can be found in your house, your

school, at the soccer field, or baseball diamond. Use the illustration

on these two pages. Identify and list as many examples as you can

of electricity being used.

With your partner or group, share your list of examples. Group all the examples in categories that make sense to your group.Label each category. Share your group’s ideaswith the class.

1. After listening to the other groups, whatcategories would you use to classify yourlist now? Reclassify your list using thesenew categories. Don’t forget to include anyadditional observations you have made.

2. What is one example of electricity youwould add to the picture? Draw what youthink this would look like.

Electricity is EverywhereElectricity Is Everywhere

Write

3. Use the words in your list. Make a cinquain poem. A cinquain poem has fivelines. The first line is one word on thetopic (a noun). The second line is twodescribing words (adjectives). The thirdline is three action words (verbs). Thefourth line is a four-word phrase describing a feeling. The fifth line is another word for the topic.

ELECTRICITY 3


The Shocking Background to Electricity

If you want to operate a portable radio or walkman, you need batteries.These batteries can be purchased at most stores. Sometimes they arerechargeable. This has not always been the case. Imagine yourself backin the past, before television, cars, and light bulbs. You are now 200years back in time. Canada will not become a country for another 50years. There were no fridges to keep the food cold like the fridges we usetoday. This is because there was no electricity. What do you think peopleused to keep their food cold? Draw what you think was used to keepfood cold.

1

Review the drawing of your fridge with others in your class. Aren’t you glad that wehave access to electrical devices like fridges,ovens, and computers? How did humans discover and harness electricity? Believe it or not, it all started with a frog’s leg, a brasshook, an iron railing, and a lightning storm.

Luigi Galvani was an Italian scientist and amedical doctor. In 1786, while examining adead frog, he noticed that a spark couldmake the frog’s leg move, when two differentmetals were touching the frog’s leg. He wascurious as to why this happened. He won-dered if he could repeat the observationunder different conditions. Galvani guessedthat the spark travelled from one metal,

through the frog ’s muscle, and then into theother metal. While this later turned out to bethe correct guess, he didn’t know how thiscould happen. But he was determined to findout.

As the next lightning storm approached,Galvani used a brass hook to hold the frog’smuscle and attached this hook to an iron rail-ing. He knew the storm would create a spark.

If you finish your drawing beforethe others in your class, draw what

you think a kitchen would have lookedlike 200 years ago.

5ELECTRICITY

The spark could then travel between thebrass hook and iron railing to make the muscle move. As the rain came down and the lightning flashed around him, heobserved and recorded the changes to themuscle. He noticed that the muscle moved!Using his observations, he proposed that themuscle moved because of electricity. Whilethere was much excitement in his town andcountry about the discovery of electricity, itwas only the beginning of the investigationfor scientists all around the world.

Electrical MusclesIf a person has a leg or arm amputated, it is usually replaced with a device called a prosthesis, or artificial leg or arm. Today, scientists are investigating ways to make artificial legs or arms move. Just like Galvani’sexperiments, they are using electricity to makean arm move up and down or a leg bend at theknee.

In 1796, after Galvani’s muscle experiment,another scientist from Italy, Alessandro Volta,wondered if he could make electricity ratherthan observe it. Instead of using a frog’s muscle, Volta used different liquids. Heplaced these liquids in bowls and then connected the bowls with pieces of metal.

Volta discovered that when he used saltwaterin the bowl and connected the bowls withcopper and zinc metal, he could produce aspark. This was very exciting because hedesigned a chemical cell which would soonbecome a battery!

1. Imagine life 200 years ago, without electrical devices. Which of these electrical devices would you miss most?

2. Describe what a day in your life would belike, if you had no electricity.

3. Work with a small group. Read and discussthe following statement: “We are moredependent on electricity than people in thepast.” Present your ideas to the class.

As you learn about electricity, you willbuild an Electric Timeline. The ElectricTimeline will be a visual representationof important inventors or inventions inelectricity. Start your Timeline withGalvani’s discovery about electricity in 1786.

PresentDiscussWrite

In 1967, then 17-year-old Richard Keefer ofOntario invented a battery that could run ongarbage! The battery lasted longer than storebought batteries and cost about the same price.


Characteristics of Electricity

You now know about the discovery of electricity and batteries by scientists over200 years ago. It is time for you to explorethe characteristics of electricity. Before you start, write down your thoughts about the following statements and make sure to include an explanation if you can.

• Can you make electricity with a fruit and six cents?

• Can electricity make objects move?

• Can electricity go through a toothpick, fork, or straw?

2

Your teacher will set up three electricalexploration centres. At each centre, you willcomplete the procedure and answer the questions. When instructed by your teacher,move to the next centre.

Electrical Lemon CentreCentre 1: Determine if foods can act like abattery and light a light-emitting diode.

Procedure

Materials for each group:1 lemon

1 banana

1 orange

1 slice of bread

1 penny

1 nickel

2 wires with alligator clips (each wireabout 30 cm long)

1 small type of light bulb called a light-emitting diode or LED

Always remember to clean upyour centre so that someone else

can use the equipment.

7ELECTRICITY

Do you think any of these foods canmake the LED light up? Record yourprediction.

Connect one of the wires to the LED byattaching the wire to one of the LEDmetal ends. Attach the other wire to theother metal end of the LED.

Insert the penny into one of the foods.

Insert the nickel into the same food,about 3 cm from the penny.

Connect one of the wire ends to thepenny and the other wire end to thenickel.

Observe the LED. Record your observations.

Repeat steps 3 to 6 for each food.

Reread your prediction. Were you surprised by the results of this investigation? Describe your thoughtsafter you tested the first food.

If Time Allows

Which food do you think made the bestbattery? Explain.

Where do you think the battery in foodsreceives its energy from to light up theLED?

Identify and describe any energy transformations you think are occurring,when the food lights up the LED.

Lights On–Lights Off CentreCentre 2: Determine which materials allowelectricity to pass through them.

Procedure

To test which materials will allow elec-tricity to pass through them, you willneed to construct an electrical tester.

Connect one end of a wire to the end ofthe battery labelled +. Connect anotherend of a wire to the end of the batterylabeled –. Use the wire connected to the+ end of the battery, and connect it toone of the LED metal ends. Take a thirdwire and connect it to the other metalend of the LED. You should now have two wires

2

1

Materials for each group:1 metal spoon

1 piece of wood

1 quarter

1 pen

6V battery

1 glass of water

1 glass of saltwater

1 LED


11

10

9

Repeat steps 4 to 8 for one of thefoods, but increase and decrease the distance between the penny and the nickel. Does changing the distance havean effect on the LED?

87

6

5

43

2

1

continue…

When electricity goes through the LED, it lights up.


that each have an end that is not con-nected to anything. Your electrical testershould look like the diagram.

Make a list of the remaining materials atyour centre. These are the materials youwill be testing. Add two columns besidethe list of materials. Label one columnPrediction and one column Observation.

Select one of the remaining materials.Connect your electrical tester to it byattaching one wire end to one end of thematerial, and the other wire end to theother end of the material. The distancebetween the two wires should be about5 cm.

Observe and record your observations.

Disconnect the wires from the material.

Repeat steps 4 to 6 until all objects havebeen tested.

If Time Allows

If Time Allows

Any material that allows electricity topass through it is called a conductor.Any material that does not allow electricity to pass though it is called an insulator. What material would you use to make a light bulb go on – a conductor or an insulator?

Based on your investigation, whichmaterials would make good conductors?

Describe a situation where an insulatoris used in an electrical device.

10

9

8

Repeat steps 4 to 6 for one of theobjects, but increase and decrease thedistance between the two wires. Doesdistance between the wires affect thebrightness of the LED?

Pick two additional objects in theroom to test. Try to select one object youthink will make the LED come on, andanother object that will keep the LED off. Record your predictions and observations in the table.

765

4

Material

metal spoon

piece of wood

quarter

pen

glass of water

glass of saltwater

Prediction Observation

3

…

9ELECTRICITY

Electricity–TransformingEnergy CentreCentre 3: Identify and describe how eachtoy transforms electrical energy into otherforms of energy.

Procedure

Turn on each of the toys and observehow each works.

Turn off the toys.

List and describe the characteristicswhich all three toys have in common.

List and describe the characteristics thatmake each toy different from the others.

Which characteristics can you observeonly when the toys are operating?

Energy transformations occur whenelectrical energy is converted to heatenergy, mechanical energy, and chemicalenergy. Describe examples of energytransformations you observed in thetoys.

1. Use the information from the threeactivities. Create a mind map thatrepresents your understanding of thecharacteristics of electricity. To help you, start with a central picturerepresenting a situation that useselectricity.

2. Complete the sentence: “I know electricitycan move from one place to anotherbecause...”

Write

6

5

4

32

1

Materials for each group:a toy monkey that makes noise (or a toythat talks)

a toy robot (or a toy with lights)

a toy police car (or a toy that moves)


Where Does ElectricityCome From?

Before you make a decision, it is important to have all the informationthat will help you make that decision. Would you buy a game for yourfriend without knowing if she would like it? Would you go on a trip with-out making sure you knew how to get there and where you would stay?

You can find some of this information by asking someone. Otherinformation needs to be researched. When you do your research, it isimportant to keep all the information organized. One method oforganizing information is in a + and – chart. This type of chart allows youto identify the positive and negative characteristics of the particularsubject you are studying. Look at the chart. This is an example of how one student listed the information using the + and – to help him decide if he should buy a bicycle.

3

A + and – chart can also be used for collect-ing science information. You are going toread about five different ways to generateelectricity. Each way has positive and nega-tive effects on your community and the environment. Work with a partner. Create a + and – chart for the different ways to generate electricity.

There are two major categories for classify-ing types of energy resources — renewable

and non-renewable. A renewable energyresource can be used over and over. It isnever used up. Hydroelectricity, wind, andsolar energy are examples of renewable energy resources. A non-renewable energyresource can only be used once. Coal is anexample of a non-renewable energy source.

• Would like to buy a bike

• could ride it to school

• could ride it to music lessons

• could ride it to baseball practice

• still have to save more money for bike

• need a place to store bike

• need to buy a bike helmet and a lock

• not all my friends have bikes

SHOULD I BUY A BIKE?

+ -

11ELECTRICITY

Renewable Energy ResourcesHydroelectricity Hydroelectric dams create electricity byhaving a flow of water turn a generator. Agenerator is a device that can createelectricity, if it can be made to spin. Thewater needed to spin the generator usuallycomes from a river, that has been blocked bya dam. The water that is blocked by the damis called a reservoir. This reservoir can beused for both recreational purposes and farmirrigation. It ensures that there will always bewater available to turn the generators andmake electricity. Electrical generatorsoperate without creating air pollution and arereasonably cheap to operate.

Unfortunately, the large dams needed for theproduction of electricity are expensive tobuild. For each dam there is only a limitednumber of spots where they can be built.Once the dam is built, the reservoirs candestroy local ecosystems and flood agricultural land. One characteristic of hydroelectric dams is the transmission linesneeded to carry the electricity from the damsto cities in Canada. These transmission linesare usually long and expensive to build.

Solar EnergySolar energy uses the energy from the sunand transforms it into other forms of energy.For example, the sun could be used to heatwater for showers, washing dishes, and otherhousehold needs. This is called passive

solar heating. Active solar heating occurswhen solar energy is used in conjunctionwith other electrical devices.

Solar energy is available everywhere the sunshines. It is simple to use. Devices such assolar panels can be added to houses quiteeasily. There is no pollution created whensolar energy is used to generate electricity.

However, using solar energy to generate electricity does have several problems. Thesun only shines for part of the day, and some

The James Bay LG 3 Dam and a generator inside a dam produce electrical energy.


days may be cloudy. A solar cell used to generate electricity is quite expensive. Overtime it is expected that costs will get cheaper.Generating solar energy takes up a lot ofspace. Most solar-generated electricity is produced on a small scale because it wouldtake a large area of land to produce a vastamount of electricity.

WindCollecting energy from the wind requires awindmill, turbine, or blade to catch and turn

in the wind. There are many different typesof devices that can be used. Four of the morecommon types are pictured here. Each kindhas been used in Canada, but the multibladeand two- or three-blade high speed rotors arethe most common.

Wind is free, renewable, and pollution free.Windmills can be set up faster than dams orcoal power plants. Unfortunately wind speedis variable, turbines break down, birds can bekilled flying into them, and the electricity isexpensive to generate.

From left to right, clockwise: Multiblade, three-blade high speed rotor, and two vertical axis wind generators.

13ELECTRICITY

Non-Renewable Energy ResourcesNuclear EnergyAbout 50 years ago a process to control thebreakdown of the smallest units of matterwas discovered. During the breakdown ofmatter, energy was given off. This energy canbe harnessed and used to produce electricity.The most common material used for this process is uranium. The production of electricity occurs in a nuclear power plant.Canadian scientists and engineers havedeveloped one type of nuclear power plantcalled the Canada Deuterium-Uranium reactor, or CANDU reactor.

The CANDU reactor converts the energygiven off from the breakdown of matter toheat water into steam. The steam is thenused to spin generators to create electricity.

The cost of uranium fuel is relatively cheap.Uranium can be found in many parts of theworld. Nuclear power plants do not produceair pollution that cause environmental con-cerns like acid rain. For many countries, theuse of nuclear energy is an option if no otherforms of energy production are available.

The use of nuclear energy requires severalconsiderations. There are only about another100 years of uranium supply left for use. A nuclear power plant is expensive to build.A nuclear power plant functions for 30 to 50 years before it must be dismantled. Thewaste from a nuclear power plant is highlyradioactive and must be carefully handledand stored for a long period of time. Whilethe chance of a nuclear accident is low, anymajor incident would have an impact on thewhole country.

A nuclear power plant in Pickering using the CANDU reactor


CoalCoal is mined in all the provinces of Canada,except Manitoba and Quebec. Once minedfrom the ground, it is commonly burned tomake electricity and steel. In fact, almost half

of the world’s electricity comes from burningcoal. To generate electricity, coal is burned toheat water into steam. The steam is then usedto spin generators to create electricity. This issimilar to the generators in dams, except thatin dams water is used instead of steam.

Using coal for making electricity is relativelycheap, and the world has a large quantity ofcoal available. An added benefit of using coalis that other products can be made from it.These products include fertilizers, paints, andplastics.

However, using coal has certain disadvan-tages too. Mining coal can be dangerous anddisruptive to the environment. Burning coalcan create air and water pollution. As coal isnon-renewable, it will eventually be used up,or be too expensive to mine.

1. Compare your + and – chart with anothergroup in your class. Identify areas whereyour charts are the same and where theyare different.

2. Discuss the differences in the charts.

3. Write a paragraph that describes the positive and negative effects of the fiveenergy sources.

4. A new electrical generation facility isgoing to be installed in your area. Write aparagraph explaining what energy sourceto use. Use the information in this activity.Research any additional information in thelibrary or on the Internet. Your paragraphshould include:

• the reason you chose the energy sourceyou did

• how expensive the method is

• what effect it has on the environmentand the natural resources

Assume your area has equal access to allenergy resources.

Add any important energy discoveriesto your Electric Timeline. Can you addanother important discovery or inventorthat isn’t in this activity?

DiscussWrite

15ELECTRICITY

Light Up the Class

Light bulbs, wires, batteries, and switches. These are all importantin making electrical circuits. But, how do you get them to worktogether? There is only one way to find out. Try it!

4

Your task is to solve each electro problem.Use the materials from the list. When youthink you have solved the problem, drawyour solution. Have your teacher check it.

Electro Problem 1How can you make a light bulb go on?

Electro Problem 2Can you make a light bulb go on and offusing the switch?

Electro Problem 3Can you have two light bulbs on at the sametime?

Electro Problem 4 Can you make two lights go on, but whenyou unplug one of the lights, the other lightstays on? Hint: You may need to share yourmaterials with another group.

Material for each group:2 light bulbs and light bulb holders


6V battery

1 switch


1. What materials did you need to make alight bulb light?

2. Which of the diagrams below will make alight bulb light?

3. In your own words, explain how you thinka light bulb goes on when it is connectedto a battery.

Write

The first light bulb was invented byThomas Edison in 1879. During his life-time, Edison developed 1093 inventions.Two of his inventions are the motionpicture camera and the phonograph.Add Edison to your Electric Timeline.

17ELECTRICITY

Key Features ofElectrical Circuits

You are now an official investigator of electrical circuits. As with any goodinvestigator, it is important to make sure that everyone you work with usesthe same terms and language. Working with electrical circuits is no different. You may have noticed that you and your partner sometimes usedifferent words for the same thing. This could get very confusing – fast!

To help reduce confusion, there are terms and symbols connected witheach piece of electrical equipment.

5

As you read this lesson, you will keep a listof terms and symbols that are new to you oryour partner on an electrical place mat. Theelectrical place mat should be a large pieceof paper between you and your partner. Asyou see a term or symbol that is new to you,write it down anywhere on the paper.

Key Features of an Electrical SystemConducting MaterialAny material that can carry electricity is con-ducting material. Usually the common termfor this material is called a wire. A wire isdrawn in either a straight line or at a rightangle if the wire changes direction.

Electrical DeviceAn electrical device is anything that requireselectricity to operate. A radio, television,computer, walkman, light bulb or LED are allexamples of electrical devices.

For your activity, light bulbs and LEDs willalmost always be used. The symbol for a lightbulb is:

The symbol for an LED is:

LED

Light Bulb

Wires


Energy Source All circuits need some type of energy source.The energy source for the circuits you willuse is a battery or electric cell. It is called aprimary cell if it cannot be recharged, and asecondary cell if it can be recharged.

The symbol for a cell or battery is:

Switch or ControlThere are many different types of switchesavailable. Each switch can create a differentway to control an electrical device. Forexample, think of a light switch. This kind ofswitch is called a toggle switch. Switchesthat can perform a similar function are calleda slide switch and a popper switch. Canyou think of an electrical device where youhave seen these switches working?

Switches can also be used to control electrical devices by detecting, pressure,heat, and light.

Battery or cell

Sliding the switchfrom one side to theother turns the circuitfrom off to on. Slidingthe switch back turnsthe circuit off.

Pushing the switchturns the circuit fromoff to on. Pushing itagain turns it from on to off.

The reed switch works when two wires arepressed together to complete a circuit. Thisswitch could be used under a doormat and beconnected to the doorbell. When someone stepson the mat, the doorbell rings.

The tilt switch can be found in a thermostat. Asthe temperature goes down, the bi-metal stripbends and moves the switch to the right. The mer-cury rolls to the right and connects the two wires.The thermostat will turn the heater on. As theroom heats up, the bi-metal strip moves the otherway. The mercury rolls back to the other side anddisconnects the wires. The heater turns off.

The photoelectric cell detects light and produceselectricity. This type of cell is also used in solarenergy. When there is light, the circuit is on;when it is dark, the circuit is off.

19ELECTRICITY

For your activity, the symbol for a switch is:

Use these symbols to draw your circuits.Anyone who has studied electricity will beable to read them. Make sure that your workis neat and clearly labelled.

This is an example of a simple circuit.

This is the simple circuit drawn with symbols.

1. Work in groups of four. Compare yourelectric place mats. Circle the words thatno one in your group can explain ordefine. Post those words on the board orchart. Discuss the definitions as a class.

2. Use your electric place mat and the wordsand definitions discussed in class. Make aconcept map of all the terms.

3. Draw the following circuits using the correct symbols.

a. One battery connected to two lightbulbs.

b. One battery and one LED that can beturned off and on with a switch.

c. One battery and two light bulbs with aswitch that can turn off both lights atthe same time.

d. One battery and two LEDS with twoswitches so that one light can be offand one light can be on.

4. Design on paper a security flashlight thathas a switch that works by movement orpressure.

If Time AllowsTry and build the device you designed

in question 4.

WriteDiscuss

Closed SwitchOpen Switch


Different Needs,Different Circuits

Now that you know about the key features of an electrical circuit,you can investigate different types of circuits. In the Light Up theClass activity, you started to build electrical circuits to solve aparticular problem. In the previous activity, you identified the keyfeatures of an electrical circuit. Now you will use your understandingof electrical circuits to build two types of circuits. They are a seriescircuit and a parallel circuit. All circuits can be classified as one ofthese two types.

6

Series CircuitProcedure

Connect one end of the wire to one endof the battery.

Connect the other end of the wire to thelight bulb holder.

Using another wire, attach one end tothe other side of the light bulb holder.

Attach the other end of the wire to thebattery. If the light bulb goes on, youhave a series circuit!

4

3

2

1

Materials for each pair:2 light bulbs and bulb holders


6V battery

Safety CautionMake sure your hands are dry when touch-ing electrical appliances and switches.

When wiring a parallel circuit, make sureit is disconnected from the battery to prevent shock.

21ELECTRICITY

Circuit Check

Disconnect one of the wires from thebattery. Insert another light bulb in theseries circuit.

Use the free end of the wire to attach tothe light bulb holder.

Using another wire, attach one end tothe other side of the light bulb holderand the other end to the battery. The diagram shows a completed circuit.

Unhook one of the light bulbs. Describewhat happens.

Parallel CircuitProcedure

Connect one end of the wire to one endof the battery.

At the free end of the wire, connect twoother ends of wires. Check the diagramto make sure you have attached thewires correctly.

Connect a light bulb to one of the freeends. Use a second light bulb and connect it to the other free end.

Repeat steps 1 and 2 with the other endof the battery. You should now have fourwires to be connected. Two have lightbulbs at the end, and two have nothing.Can you describe what the circuit lookslike? What type of food does it look like?

4

3

2

1

8

7

6

5

A series circuit can be identified byhaving one loop. If you can place yourfinger on any part of the circuit and tracea path back to the start, you have aseries circuit.

continue…


Circuit Check

Connect the two free ends of the wiresto the two light bulbs.

Unhook one of the light bulbs. Does theother light bulb stay on? Record yourobservations.

1. Give examples of similarities between aseries and a parallel circuit. Give examplesof differences between a series and a parallel circuit.

2. Why do you think the two light bulbs goout when one light bulb was unhooked inthe series circuit?

3. Why do you think one light bulb stayed onwhen the other light bulb was unhooked inthe parallel circuit?

4. Can you describe a situation where aseries circuit could be used to operate an electrical device?

5. Can you describe a situation where a parallel circuit could be used to operate an electrical device?

Write

6

5

A parallel circuit can be recognized by having more than one loop. If you can place your finger on any part of the circuit and trace a path, there will a pointwhere you have to choose which wire tofollow. The diagram shows a completedcircuit.

…

The dots in the above parallel circuit represent aconnection between two or more wires.

23ELECTRICITY

Fixing Electrical Problems

There are so many uses for electricity. But what happens when something breaks down? Maybe your television doesn’t have sound whenit is turned on or your hair dryer doesn’t blow any hot air. What do youdo? Many people take their broken appliances to a repair shop or have atechnician come to the home.

When an electrical appliance is sent for repairs, the technician has todetermine what is wrong. This process is called troubleshooting. Troubleshooting requires a person to ask a series of yes or no questions todetermine the problem. Once the problem is known, it can be fixed. Youare going to have an opportunity to develop your troubleshooting skills,and then a chance to try and solve an electrical problem.

7

Before you begin troubleshooting the electrical problems, here is a guide to helpyou. Ask yourself each question and if the

answer is yes, go on to the next one. If theanswer is no, you have found one of theproblems and will need to fix it.

Question

1. Are the wires to the battery connected?

2. If there is a switch, is it on?

3. Are all the connections in the circuit attached properly?

4. If the circuit is a series circuit, is there only one complete loop?

5. If the circuit is a parallel circuit, do any of the wires start and end at the same place?

6. Does the electrical device (like a light bulb) work?

Response

Check connections to battery. Reconnect if necessary.

Check to see if switch is on or stuck. Turn switch on, off, and on.

Check all connections in the circuit. Reconnect if necessary. Check to see if anything is blocking part of the circuit.

Trace a path from one battery end, through the circuit and back to the other end of the battery. If one full loop not possible, rebuild circuit.

Ensure none of wires start and end at the same place. Rebuild circuit if some wires are not properly attached.

Remove electrical device and replace with an electrical device you know works. If second electrical device doesn’t work, the problem is not the electrical device. Recheck your answers from steps 1 to 5.


Problem 1Why won’t this flashlight turn on?

Problem 2Why won’t the light bulbs light in the circuit?

Problem 3Why won’t the doorbell ring?

Problem 4Why won’t the bulbs light up?

Problem 5Why won’t one speaker play music?

Problem 6Why won’t one of the lights go on?

Use the troubleshooting guide. Determine what is wrong with these six circuits.

Remember to write down your solution to each problem.

25ELECTRICITY

You have practised developing your troubleshooting skills. Now, solve the

following problem. It was sent to a companythat makes night lights. Send a response toMr. Ohm with suggestions for fixing his broken lamp.

Write

To: Bright Nite Light Corp.

From: Mr. Ohm

Re: Broken “Bright Light” night lamp

I would like to ask for your assistance in

fixing my broken “Bright Light“ night

lamp. My daughter really likes her night

lamp, but I am unable to fix it. I have

taken the lamp apart and drawn what

it looks like. I would appreciate any

suggestions you could make to

help me fix the lamp.

Thank you for your help.

Sincerely,

Mr. Ohm

Mr. Ohm

The first illuminated glass sign wasinvented by John B. Studley of NovaScotia in 1858. The sign used gas burners behind the glass sign ratherthan electrical light bulbs. Add Studleyto the Electric Timeline.


A Special Kind of Electricity – Static Electricity

In previous activities, you have observed batteries turning chemical energyto electrical energy, which was transformed into sound, light, and motionenergy. You have also observed that materials like salt water and metalscan conduct electricity. You can also provide an example of electricity mov-ing. For example, when you used your electrical tester and the metal spoon,electricity flowed from the battery, through the wires and the spoon to lightthe LED, and then back to the battery. In some situations, electricity doesnot move. This is called static electricity. Can you think of any examples ofstatic electricity? Share your examples with a partner. Make a list with twocolumns. In the first column list the examples which you both agree arestatic electricity. In the second column list the examples which you andyour partner are not sure are static electricity.

8

The following advertisement about MagicalBalloons was found on the Internet. Yourtask is to determine if your class should purchase a Magical Balloon. You will need to collect evidence to support your decision.Try to prove or disprove the claims in theadvertisement by reproducing the “magicalqualities” of the balloon.

Materials for each pair:1 balloon

10 small pieces of paper

1 pencil

27ELECTRICITY

The Magical Balloon is an example of staticelectricity. Static electricity stays in oneplace. In this case, it stays on the balloon.Your investigation showed that static electricity can cause objects to move or stickto one another.

1. Determine which of the eight statementsgiven below are characteristics of staticelectricity, and which are characteristicsof current electricity:

• You rub your feet on the carpet, touchsomething made of metal and get ashock.

• You forget to use fabric softener whenyou wash your clothes, and they sticktogether when you take them out of thedryer.

• You turn on the television.

• On a cold evening, your jacket crackleswhen you take it off.

• A flashlight is turned on.

• Dust gathers under your bed.

• The school bell rings.

• You play a computer game.

2. Describe a situation in your life whereboth static and current electricity could beobserved at the same time. Start yourdescription with the following: “As Iwalked into my house …”

3. Review the list you and your partner madeat the start of this activity. Look at theexamples in both columns. Are there anychanges or additions you would make tothe list? If so, which ones would youchange or add?

Write


Learning About Magnets

Have you ever played with magnets? Maybe you have seen one in a toyor a game or at school. They come in different shapes, sizes, and colours.They can pick up things, hold on to things, and move objects away.Sometimes magnets stick together or move away from each other.Magnetism is the force around a magnet. It is strongest at a magnet’spoles. The poles are labelled N and S. N is for the North Pole of the magnet, and S is for the South Pole of the magnet. What would happen ifyou put the N of one magnet near the N of another magnet? What otherway could you place two magnets so they would push away from eachother? Which way could you place two magnets so they would sticktogether?

9

Magnets can exert a force on an object andmake it move without touching it. Some people may have called this magic a longtime ago. But you can observe this effect byusing a bar magnet and some iron filings.Place a piece of paper on your desk. Sprinklesome iron filings on the paper. Stick the

magnet underneath the desk. Move the magnet around. Can you see the iron filingsmove? This is an example of magnetic force

acting on the iron filings without actuallytouching the iron filings.

Let’s look at another example of magneticforce acting on an object at a distance.

29ELECTRICITY

ProcedurePlace the compass in the centre of yourdesk. Note the direction the compassneedle is pointing.

Bring the magnet close to the compassneedle, but do not touch the compass.Move the magnet around the compass.Describe what happens. Include wordslike attract, move, and point in yourdescription.

Use the other end of your magnet.Repeat step 2.

Position the magnet so that it no longeraffects the compass needle.

Now place the wire over the compass.Make sure it is positioned on top of thecompass needle. See the photograph.Place a piece of tape on each side of thewire to hold it in place.

Connect one end of the wire to one endof the battery. Connect the other end ofthe wire to the other end of the battery.Quickly observe what happens to thecompass needle.

Unhook one end of the wire from thebattery. Observe what happens to thecompass needle.

Repeat steps 6 and 7 to confirm yourobservations. Describe what youobserved. Your description should startwith: “When electricity flowed throughthe wire, I observed …”

1. Describe what was similar between usingthe magnet and the compass, and the wirewith electricity running through it and thecompass.

2. In your own words, can you make a rulethat would describe this situation?

3. Brainstorm with a partner possible uses ofyour electricity-magnet discovery.

In 1820, Danish teacher Hans ChristianOersted was the first person to discoverthat an electric current could cause acompass needle to move. Add Oerstedto your Electric Timeline.

DiscussWrite

8

7

6

5

4

3

2

1

Material for each student:6V battery

1 wire (about 30 cm long)

1 compass

1 bar magnet


Electrical Picker Uppers

Did you know there are different kinds of magnets? Some magnets are permanent. These magnets stay magnetized for long periods of time. Other magnetsare considered temporary. They can turn theirmagnetism on and off. For example, amotor, a fire alarm bell, and a telephoneall require temporary magnets calledelectromagnets.

In the last activity, you learned thata compass needle moved whenelectricity moved through the wire.The electricity acted like atemporary magnet. As soon as theelectricity was off, the compassreturned to its normal position.

You are going to build an electromagnet.By the end of the activity, you should beable to describe its characteristics. Before youstart, discuss with your partner how to get a paperclip and an iron nail to stick together.

10

Materials for each pair:6V battery

3 wires with bare ends (about 30 cm,45 cm, and 60 cm each)

1 iron nail

1 pencil

1 plastic film canister

40 paper clips

Safety CautionBe careful! The nail will get hot veryquickly. Do not touch the wire to thebattery for a long time.

31ELECTRICITY

ProcedureTake the 30 cm wire and wrap it aroundthe nail ten times. Attach the ends of thewire to the battery. Touch the nail andcoil of wire to the pile of paper clips.Record your first response after you seethe nail touch the paper clips.

Unhook one of the wires from the battery. Record your observations.

Discuss your observations with yourpartner. Why do you think the paperclips are attached to the nail?

What do you think will happen if thenumber of coils around the nail isdecreased or increased? Make a tablelike the one seen here. Predict how manypaper clips will be picked up with eachnumber of coils. Test your prediction.

Instead of changing the number of coilsin the wire, use the pencil to wrap thewire around. Before you start, predictwhich material will work better – thepencil or the plastic film canister?

Wrap 20 coils around the pencil. Attachthe wires to the battery. Dip the penciland coils into the pile of paper clips.Record how many paper clips werepicked up. Unhook one wire from thebattery.

Repeat step 6 with the plastic film canister.

1. Draw a bar graph to show how manypaper clips were picked up with a particular number of coils. What numberof coils picked up the most paper clips?

2. Which material picked up the most paperclips? Which picked up the least?

3. Describe a situation where you think anelectromagnet would make a job easier.

One of the most common uses of an electromagnet is in a motor or generator. In a generator an electro-magnet is spun around to produce electricity. In a previous activity, you read about generators. Can youremember what they were used for?The first generator was developed byMichael Faraday of England in 1831. A motor can use electricity to perform a function or activity. Can you find outwhen and where the first motor wasinvented? Add these dates to yourElectric Timeline.

Write

7

6

5

Number of coils

15102040

Predicted Number of Paper Clipspicked up

Actual Number of Paper Clipspicked up

4

3

2

1


Talking around the World – Thanks toCanadians

Talking on the phone, watching television, and sending an e-mail—whatdo these activities have in common? If you said they are all forms ofcommunication, you would be right! These forms of communication alsorely on electricity.

Before electricity, people had difficulty communicating across great distances. Sometimes it took weeks or months to get a message fromHalifax to Vancouver. Now you can talk to almost anyone in the worldinstantly. How does this happen? Let’s start with a Canadian discovery.

11

“To be or not to be” are words spoken byHamlet, the hero in the play Hamlet, writtenby William Shakespeare. They were also the

first words spoken on a long distance telephone call from the Ontario inventor,Alexander Graham Bell. It was the summerof 1876. Bell used, among other things, a thin sheet of metal, a coil of wire wrappedaround a magnet, and a battery to create atelephone. This device was able to convertsound into electricity, and back to sound.Now thousands of kilometres can separatewhere the sound was made and where it washeard. Canadians can now talk to each otherinstantly rather than wait weeks for a letter.

Did you know that the first owner of a telephone in Canada was Prime MinisterAlexander MacKenzie? He used the phone to talk to the Governor-General in 1877.

33ELECTRICITY

When phones were first invented the personusing the phone had to move the receiverbetween the ear and the mouth. Sometimespeople got confused and talked when theyshould have listened or listened when theyshould have talked! In 1878, Cyril Duquet ofQuebec designed a phone receiver to haveboth an ear and voice piece like the phonesof today.

Canadians continued to be involved ininventing devices that used electricity tosend signals over great distances. The firstwireless voice message was sent by Quebecinventor Reginald A. Fessenden in 1900. Hisfirst message only travelled 2 km. In 1906, theworld started to communicate by sendingelectronic signals through the atmosphere.Using a microphone, Fessenden’s voice wasconverted to a radio signal that could be sentand received at another location. The key tothe operation? All of his devices requiredelectricity.

One person talks on his or her phone, and thesound is converted into an electronic signalthat is sent to the satellite. The satellite thensends the signal back down to the person youare speaking to.


DID YOU KNOW THAT CANADIANS DID THIS?

In 1924, Sir William Stephenson ofManitoba invented a method of sendingpictures for newspapers over phonelines.

In 1927, Edward Samuels Rogers ofOntario made the first radio that couldbe plugged into a wall outlet.

In 1942, Donald L. Hings of BritishColumbia invented the portabletransceiver, or Walkie-Talkie.

In 1972, Anik 1 was launched. It wasthe world’s first geostationary communications satellite. This satellitewas the first one to allow ordinarypeople to communicate with each other by having their voices sentelectronically through space.

In 1987, when Anita Luszszak was 15years old, she developed a pulsatinggenerator that used less energy togenerate electrical power than theconventional power generators. TheAlbertan student won a gold medal atan international competition forinventors.

In 1998, electric cars have Canadianinventors very busy. Pierre Couture ofQuebec is developing a car that hasfour electric motors on each wheel ofthe car. Ballard Power Systems Inc. ofBritish Columbia is developing a fuelcell that will power the electric cars ofthe future.

From satellites to fiber optic

communications, Canadians are leaders inthe world of global communications. Usingelectricity, Canadians have found many waysto send signals throughout the world.

1. Discuss with your classmates what youthink will be the communication devicesof the future.

2. Can you add any more Canadian inven-tions that use electricity, especially onesthat convert electricity into a signal?Research this in the library and on theInternet.

In 1901, the first radio transmissionacross the Atlantic Ocean occurredbetween the southwestern tip ofEngland and St. John’s, Newfoundland.This experiment was designed byGuglielmo Marconi of Italy. AddMarconi and the other inventors youhave just read about to your ElectricTimeline.

WriteDiscuss

35ELECTRICITY

Electricity – Use it Carefully

Electricity is something most of us assume will always be available.However, in many countries electricity is not as common. In Canada youcan flip a switch and light a room, or turn on a television to watch ashow. Many people in other countries do not have this same lifestyle. Youare going to have an opportunity to compare the different energylifestyles between a Canadian and a Mongolian student.

Before you make an energy comparison between two countries, you willneed to have a method on which to base your comparison on. Theamount of electricity used by an appliance is measured in a unit calledkilowatt hours, or kWh. A kWh costs about five cents. A television thatuses 1 kWh would cost five cents for every hour that it is turned on.A television turned on for three hours would cost fifteen cents.

12

The table shows approximately how manykilowatt hours an electrical appliance uses ina typical day.

1 kWh = 5 cents2 kWh = 10 cents 3 kWh = 15 cents

Electrical appliance

Refrigerator

One load of laundry and dryer

Water heater

Stove

Electric kettle

Light bulb

Radio

Colour television

Black-and-white television

Hair dryer

Electric clock

Stereo

Dishwasher

Shower

Energy usage

4 kWh

5 kWh

32 kWh

7 kWh

1.5 kWh

1 kWh

0.25 kWh

2 kWh

1 kWh

0.2 kWh

0.25 kWh

0.75 kWh

1 kWh

1 kWh


Nine-year old Batsuury climbs out of bed andgets ready for school. She can see her momand dad are already up and they have turnedon the light bulb. Living in a one-room tentallows her to see her dad starting a fire in thestove. The stove also heats the tent. Hermom starts breakfast as she listens to thedaily news report on their black-and-whitetelevision. Her mom asks her to go outside to the ice box and bring in the milk. AsBatsuury goes outside the tent, or ger, shebarely notices the sun. There is a haze in theair created by the coal-generating powerplant. As she brings in the milk, her momplugs in the electric kettle to make tea forthe family. Batsuury lives with her mother,father, brother, sister, aunt, and cousin. Whilebreakfast is being made, she puts on herschool uniform. Another day has begun.

Halfway around the world, Jennifer is gettingready to go to a surprise birthday party. Sheand her dad have spent the afternoon bakinga cake. Her brother, Rhys, wasn’t interestedin helping, so he is playing video games on

the colour television. Her mom is at work. As the cake is baking, Jennifer cleans thekitchen and by accident drops the leftovercake batter. The batter lands everywhere,including on her clothes. Luckily, she hastime to take a shower and change her clothesbefore the party. While she blow-dries herhair, she listens to her favourite music on herclock radio. When she is ready to go, shegrabs the cake from the refrigerator andthanks her dad for helping her. She alsopromises to clean out the dishwasher whenshe gets home.

1. Calculate how much energy in kilowatthours each girl used.

2. Is there a difference in the amount of energy the girls used? Can you provide an explanation for this difference?

3. Do you think that we use too much or notenough electricity in Canada? Explainyour answer.

Write

37ELECTRICITY

Conserving Electricity

The amount of electricity used by Canadians when compared to othercountries is considered quite high. In 1996, Canada was the sixth largestuser of electricity in the world. One of the ways to reduce our electricityuse is to conserve it when possible. If everyone conserves a small amountof electricity, this can add up to huge savings. Join your partner or smallgroup. Brainstorm all the different ways you can think of to save electricity at home and at school. When your list is complete, share it with the class.

13

In your group, design an action plan that willidentify five ways to conserve electricity. Youmay want to use the ideas from your list. Forexample, you may decide to turn out the lightin your bedroom when you are not there.This may save 1 kWh per month. If everyone in Canada did this, we would save $1.5 million a month!

1. Using your action plan, create a pledgeform. You may wish to use the sampleform provided here, or design your own.Keep this form as a reminder of the importance of conserving electricity.

2. Does your action plan cause people togain or lose jobs? How? How does it affectthe use of natural resources?

DiscussWrite

Identify a goal

Identify what must be done to meet that goal

Determine if anything will prevent you or make it difficult for you to meet your goal

Describe how you will know when you meet that goal

State your completion date

Turn out the bedroom light

When leave bedroom, turn out light

May not be last person in bedroom

Save family money on electrical energy bill

End of school year

STEPS TO AN ACTION PLAN

✔

✔

✔

✔

I,____________________ pledge to conserve

electrical energy in these ways:

1.______________________________________

2.______________________________________

3.______________________________________

4.______________________________________

5.______________________________________

Student’s signature____________________

Teachers signature____________________

DesignProject


Secret TalkGet Started

Have you ever wondered how inventions are made?

Sometimes people have an idea and other times they just

try something and see how it works. Either way, inventors

are willing to take risks and try things no one else has ever

done. Sometimes the reward for your invention can last

longer than a lifetime. An example of this is Elijah McCoy,

the inventor of the automatic oil cup and the lawn

sprinkler. He was born in Ontario in 1844 after his family

fled to Canada to escape slavery in the United States. His

inventions were so well received people referred to them

as the “Real McCoy.” This term is still used today to

indicate an object that is the actual object and not an

imitation.

You have developed an Electric Timeline to illustrate impor-

tant inventors or inventions in the area of electricity. Now

it is time to add your name and invention to the Timeline!

DesignProject

39ELECTRICITY

You will design an electrical device that willsend a signal to your friend at the other endof the room. Remember the following:

• You should be able to send the signal atany time.

• You should be able to repeat the signal.

• You should not disturb others around you,when you send the signal.

ProcedureDesign your device on paper to see whatit will look like. Label all parts. Include ashort explanation of how your devicewill work.

Build and test your device. Troubleshootif necessary.

Be prepared to answer questions aboutyour device such as:

• How does it work?

• What type of energy transformationsdoes it use?

• Could your device be used in thefuture? How? Is your device environmentally friendly?

1. Demonstrate your device to the class.

2. Suggest how you would improve yourdevice next time.

3. Add your invention and your name to yourElectric Timeline.

PresentDiscussWrite

3

2

1


Work on ItYou have been given the task of designing anautomatic electrical light system for a homeworkshop. The machines in the workshopare very noisy, so the door must be closedwhen the owner of the house is in the work-shop. Since she often carries materials in andout of the workshop, it would be helpful tohave an automatic light switch. The lightmust go on when the door closes and go offwhen the door opens. Also, there are twolights in the room that must work together.As a safety measure, the design shouldensure that one light bulb will still work ifthe other goes out.

You may use any piece of equipment discussed in this unit to design your automatic light switch. The owner would like a neat, labelled diagram and a description explaining how the electrical system will operate. She will also need a listof materials to be purchased to build theelectrical light system.

Now check your work.

My work contains a diagram, a description, and a list of materials. Each is complete.

My diagram uses appropriate symbolsand is correctly labelled.

In my design, the light goes off andon automatically when the dooropens and closes.

My design contains two lights thatwork independently.

ReviewU n i t 3

Get StartedNow it’s time to show how much you have learned about electricity.Read over what your tasks are, and talk to your teacher if you areunclear about what to do.

DemonstrateWhat You Know

41ELECTRICITY

Communicate Now it’s time to think about how well you did. Use this chart to help you score your work.Four stars is the highest score for each.

1 Star 2 Stars 3 Stars 4 Stars

• How much do you know about electricity? Look at your diagram, your list of materials, and your description. Does your work show you know

A little about Some A lot of All aboutelectricity information information electricity?

about electricity about electricity

• Look at the description of your diagram of the electrical circuit. Does your work show you have

A few of the skills Some of the skills Most of the skills All of the skillsto set up an to set up an to set up an to set up anelectrical circuit electrical circuit electrical circuit electrical circuit?

• Now look again at your description. Will it be clear and precise to a reader?

Not very clear Somewhat clear Mostly clear Very clearor precise and precise and precise and precise

• How well do you think you understand what the homeowner wanted?

Not much Some A good A completeunderstanding understanding understanding understanding

Write a short note explaining how well you think you did.


What did you learn about electricity?1. Describe some key discoveries in the

history of electricity.

2. Identify five renewable and non-renewableenergy resources. Write a description ofhow society uses one of each.

3. Draw a series circuit that has two LEDs, a battery, and a switch.

4. Draw a parallel circuit that has two lightbulbs, a battery, and a switch to turn bothlights off and on.

5. Describe a situation where a series circuitwould be used and describe a situationwhere a parallel circuit would be used.

6. Explain how you would fix this circuit tomake both light bulbs stay on all the time.

7. Describe three examples of static electricity.

8. An electromagnet has twenty coilsaround a wood stick and can pick up fivepaper clips. Describe how you couldmodify the electromagnet to pick upmore paper clips.

9. What was the importance of Fessenden’sdiscovery to electronic communication?

10. What can you do to conserve electricity?

ExplainYour Stuff

ReviewU n i t 3

43ELECTRICITY

Answer the following questions to highlightwhat you learned in this unit.

1. List three things you didn’t know beforethe unit started.

2. Describe what you liked best in this unit.

3. Give yourself a pat on the back! What didyou do well in this unit?

4. List three questions you still have aboutelectricity.

Now you know a lot aboutelectricity! Here are somethings you’ve learned:• Electricity was discovered by Luigi

Galvani after examining a spark jump froma metal to a frog’s muscle and seeing thefrog’s leg move.

• Electricity can come from a variety ofrenewable energy resources – hydro electricity, solar, and wind – and non-renewable energy resources – nuclear and coal.

• The decision to use one energy resourceover another is complex.

• Electrical circuits require a battery, wires,and an electrical device to operate. Ideallythey also have a switch to control howthey operate.

• There are electrical symbols used todescribe the setup of electrical circuits.

• The two most common types of circuitsare series and parallel circuits. Each canbe used for particular situations.

• If an electrical circuit is not working, you have to fix it using a process calledtroubleshooting.

• Static electricity is a type of electricitythat does not move, but can be observedto have an effect on other objects.

• Electricity can create a magnetic field thatcan be used in electromagnets and motors.

• Canadian inventors had an important role in the development of electronic communications.

• Electricity usage varies throughout theworld. We must all do our part to conserveelectricity.

How DidYou Do?

44

active solar heating solar energy used in conjunction with other electrical devices to create heat

battery a number of electric cells connectedtogether that supply energy

chemical energy the energy stored in thebonds between the smallest units of matter

circuit an arrangement of electrical devices thatallows electricity to flow through conductors

coal a black mineral that can be burned tomake electricity or used to make chemicals; anon-renewable resource

conductor a material that allows electricity topass through it

electrical energy energy produced by a current flowing through a wire or other object

electricity a form of energy that can flowthrough conductors

electromagnets the temporary magnets madeof an iron bar with coils of wire around it; theyact as magnets when electricity flows through thewire coils

fiber optic communications communicationby means of light signals along thin glass fibers

generator a device that creates electricity fromthe mechanical energy of the rotation of the centre of the generator

insulator a material that does not allow electricity to pass through it

kilowatt hours (kWh) a unit of measure of theamount of electricity

light bulb the common name for an electriclamp that produces light by heating a thin wirethread to a very high temperature

light-emitting diode (LED) a small type oflight bulb

magnetic force the force that acts betweentwo magnets by pulling them together or pushingthem away from each other

magnetic poles the two ends of a magnetwhere the magnetic force is strongest

magnetism the force around a magnet

non-renewable an energy resource that canonly be used once and cannot be replaced

nuclear energy the energy produced by thebreakdown of the smallest units of matter; theheat produced turns the water into steam, whichdrives the generators in nuclear power plants

parallel circuit a path of electrical current thathas more than one loop in the circuit

passive solar heating the energy from thesun used to create heat

popper switch a switch that can be pushed toturn electricity off and on

primary cell a non-rechargeable device

prosthesis an artificial body part

radioactive a property of substances that giveoff energy when their smallest units of matterdecay

renewable an energy resource that can be usedover and over or replaced

reservoir the water that is blocked by a dam

secondary cell a rechargeable device

series circuit a path of electrical current thatpasses through each device in the circuit, oneafter another; a path that has one loop

slide switch a switch used to turn electricityoff and on by moving a slider back and forth

solar energy the energy from the sun, eitherlight or heat

static electricity electricity that does not move

toggle switch a switch used to turn electricityoff and on using a lever

troubleshooting the process of discoveringand eliminating causes of trouble

uranium a radioactive metal used in nuclearpower plants

Walkie-Talkie portable transceiver invented byCanadian Donald L. Hings in 1942

wire a thin thread of metal that can carry electricity

Glossary

SCIENCE & TECHNOLOGY 6

Acknowledgments

The publisher wishes to thank the following sources for photographs, illustrations, articles, and other materi-als used in this book. Care has been taken to determine and locate ownership of copyright material used inthis text. We will gladly receive information enabling us to rectify any errors or omissions in credits.

Photographyp. 1 (centre) Richard Kaylin/Tony Stone Images, (bottom) Bob Anderson/Masterfile, p. 5 Publiphoto, p. 6PhotoDisc, Inc., p. 9 PhotoDisc, Inc., p. 10 PhotoDisc, Inc., p. 11 (top left) J.M. Petit/Publiphoto, p. 11 (topright) U.S. Dep’t of Energy/SPL/Publiphoto, p. 11 (bottom) Agence D.P.P.I./DPR/Publiphoto, p. 12 (bottomright) Edgar Bernstein/Peter Arnold, p. 12 (bottom left) A. Sirulnikoff/First Light, p. 12 (top left) Kirtley-Perkins/Visuals Unlimited, p. 12 (top right) Y. Derome/Bettmann Archive/Publiphoto, p. 13 DavidPrichard/First Light, p. 14 Colin Raw/Tony Stone Images, p. 18 (bottom left) Joe Lepiano, p. 21 (right) DaveStarrett, p. 25 (right) Dave Starrett, p. 26 Gordon Garradd/Science Photo Library/Publiphoto, p. 28 RayBoudreau, p. 29 Ray Boudreau, p. 32 Bettmann Archive/Publiphoto, p. 33 (top) Peter Steiner/First Light, p. 35 PhotoDisc, Inc.

Illustrationp. 1 (top) Doug Panton, pp. 2–3 Steve Attoe, p. 4 Joe Weissmann, p. 5 Joe Weissmann, p. 7 Pronk&Associates,p. 8 Pronk&Associates, p. 15 Pronk&Associates, p. 16 Pronk&Associates, p. 17 Pronk&Associates, p. 18 (topleft) Pronk&Associates (right) Dave McKay, p. 19 Pronk&Associates, p. 20 Pronk&Associates, p. 21 (left)Pronk&Associates, p. 22 Pronk&Associates, p. 24 (top left) Dave McKay, others Pronk&Associates, p. 25 (left)Dave McKay, p. 27 Pronk&Associates, p. 30 Dave McKay, p. 33 Dave Edmunds, p. 36 Joe Weissmann, pp. 38–39 David Bathurst, p. 42 Pronk&Associates

Cover PhotographVCG/FPG–Canada Inc.

Plant GrowthMagnetismForces and MovementStabilitySoil

Habitats LightSoundPulleys and GearsRocks and Minerals

The Human BodyChanges in MatterConservation of EnergyForces on StructuresWeather

Diversity of Living ThingsAir and FlightElectricityMotionSpace

GradeGrade

GradeGrade

GradeGrade

GradeGrade

ElectricityGradeGradeGradeGrade

addison wesley 6 science technology · 2 science & technology 6 get started electricity is...

Documents