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Teacher's Guide

Magnets andElectromagnetism

Editors:Brian A. Jerome, Ph.D.Stephanie Zak Jerome

Assistant Editor:Anneliese Brown

Graphics:Fred Thodal

Lyndsey CanfieldDean Ladago

1-800-453-8481Visual Learning CompanyMagnets and Electromagnetism

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ISBN 978-1-59234-188-7

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Table of Contents2

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A Message from our Company

Viewing Clearances

Use and Copyright

National Standards Correlations

Student Learning Objectives

Assessment

Introducing the Program

Program Viewing Suggestions

Video Script

Answer Key to Student Assessments

Answer Key to Student Activities

Pre-Test

Post-Test

Video Review

Vocabulary

Writing Activity

Build a Compass

Magnetic Fields

Exploring Electromagnetism

The Power of Water


National Standards CorrelationsBenchmarks for Science Literacy(Project 2061 - AAAS)

The Physical Setting - Forces of Nature (4G)By the end of the fi fth grade, students should know that:

National Science Education Standards(Content Standards: K-4, National Academy of Sciences)

Grades 3-5

• Without touching them, a magnet pulls on all things made of iron and either pushes or pulls on other magnets.

• Electric currents and magnets can exert a force on each other.

Physical Science - Content Standard BAs a result of activities in grades K-4, all students should understand that:

• Magnets attract and repel each other and certain kinds of other materials.

• Electricity in circuits can produce light, heat, sound, and magnetic effects. Electrical circuits require a complete loop through which an electrical current can pass.


Student Learning ObjectivesUpon viewing the video and completing the enclosed student activities, students will be able to do the following:

• Defi ne a magnet as a material that attracts iron and materials containing iron.

• Explain that magnets have a north pole and a south pole where its magnetic fi elds are strongest.

• Explain that magnets exert a force on each other, referred to as magnetic force. • Describe a fundamental rule of magnetic poles: like poles repel each other and unlike poles attract each other.

• Understand that every magnet is surrounded by a magnetic fi eld, which exerts an invisible force on magnetic materials near it.

• Understand that Earth is surrounded by an enormous magnetic fi eld, which is strongest at the Earth’s poles.

• Defi ne the magnetosphere as the region around Earth where its magnetic fi eld is located. Explain how it protects Earth from solar wind.

• Explain that electricity can create magnetism and magnetism can create electricity.

• Understand that a solenoid is a long coil of wire that produces a magnetic fi eld when electricity fl ows through it.

• Defi ne electromagnetic induction as the process of generating an electric current by passing a wire through a magnetic fi eld.

• Understand that generators rely on electromagnetic induction to produce most of the electricity we use in our homes.


The Post-Test can be utilized as an assessment tool following student completion of the program and student activities. The results of the Post-Test can be compared against the results of the Preliminary Test to assess student progress.

The Preliminary Test is an assessment tool designed to gain an understanding of students’ preexisting knowledge. It can also be used as a benchmark upon which to assess student progress based on the objectives stated on the previous pages.

Assessment

Preliminary Test (p. 14-15):

Video Review (p. 18):

Post-Test (p. 16-17):

The Video Review can be used as an assessment tool or as a student activity. There are two sections. The fi rst part contains questions displayed during the program. The second part consists of a fi ve-question video quiz to be answered at the end of the video.


Introducing the Program

Program Viewing SuggestionsThe student master “Video Review” is provided (p. 18) for distribution to students. You may choose to have your students complete this Master while viewing the program or do so upon its conclusion.

The program is approximately 14 minutes in length and includes a fi ve-question video quiz. Answers are not provided to the Video Quiz in the video, but are included in this guide on page 12. You may choose to grade student quizzes as an assessment tool or to review the answers in class.

The video is content-rich with numerous vocabulary words. For this reason you may want to periodically stop the video to review and discuss new terminology and concepts.

Before viewing the program, ask students if they have ever been lost in the woods or in a city. Next, ask the students if they know what simple device could have helped them fi nd their way. That’s right! Compasses help people move in the right direction. Explain that compasses contain a magnetized needle that is able to rotate. The needle reacts to Earth’s magnetic pole and always points north, which helps people determine the direction in which they are moving.

Ask students to describe other ways they use magnets in their everyday lives. Examples might include attaching papers and photos to a refrigerator and keeping a freezer door closed. But did they know that magnets can produce electricity? Ask students if they have ever used a generator. Explain that generators rely on spinning magnets to induce an electrical current on a wire, producing electricity. Tell students that most of the electricity they use is powered by generators. Ask students to pay close attention to the program to learn more about magnets, how they produce electricity, and how electrical current can create magnetism.


Video Script1. Do you use objects like this to hold papers on the refrigerator at home?2. Have you ever used a compass?3. Maybe you’ve noticed how your freezer door tightly seals itself.4. And you’ve probably used electric motors in things like toy trains...5. ...and electric appliances.6. If you have used any of the things just mentioned, you have used devices made of magnets or electromagnets.7. During the next few minutes, we are going to explore some of the characteristics of magnetism and electromagnetism,8. ...and investigate some of the ways they make our lives easier.9. Graphic Transition – What are Magnets?10. If you have ever played with magnets, you know that they stick together…11. ...and attract some metal objects which contain a specifi c type of material.12. You Decide!

What is this material?13. It’s iron.14. A magnet is a material which attracts iron or materials containing iron. 15. Magnets are also capable of attracting other materials, such as nickel.16. Magnets do not attract materials such as wood, plastic, or glass.17. Magnets also exhibit certain characteristics. For example, a magnet has two ends where its magnetic effects are strongest.18. The ends of a magnet are called poles.19. One pole is called the north pole and the other end is called the south pole.20. If left to freely fl oat, the north pole of the magnet will point in a northerly direction.21. Magnets come in different sizes and shapes too.22. For example, this is a bar magnet…23. ...and this is a horseshoe magnet.24. Graphic Transition – Magnetic Forces and Fields25. When you bring two magnets together, they exert a force on each other. They can either attract each other or push each other away.26. This attraction and repulsion are referred to as magnetic forces.27. Notice what happens when the north pole of one magnet is brought near the south pole of another magnet. They are attracted to each other.28. You Predict! What will happen when the north pole of this magnet is brought near the north pole of another magnet?29. As you can see, the magnets repel each other. The same holds true when two south poles are brought near one another.30. The rule for magnetic poles is: like poles repel each other and unlike poles attract each other.31. Each magnet is also surrounded by an invisible force called a magnetic fi eld, which exerts a force on magnetic materials near it.


Video Script32. The lines on this diagram illustrate the shape of the magnetic fi eld around a bar magnet.33. Watch what happens when we hold this magnet below a piece of plastic on which particles of iron are sprinkled.34. Notice how the iron particles outline the magnetic fi eld.35. This container houses a magnet which is surrounded with iron fi lings.36. Notice how the fi lings encompass the entire magnet, illustrating the fact that magnetic fi elds are three dimensional.37. Graphic Transition – Earth as a Magnet38. You may not realize it, but we live on a giant magnet.39. Just as this bar magnet is surrounded by a magnetic fi eld,…40. ...Earth is surrounded by an immense magnetic fi eld.41. This magnetic fi eld is strongest near the Earth’s poles.42. Earth’s magnetic fi eld also extends outward through the atmosphere and into space.43. The magnetosphere is the region around Earth where magnetic fi elds are located. This diagram illustrates the magnetic lines of force in the magnetosphere.44. As we will discuss later, magnetic fi elds can effect the motion of charged particles.45. The magnetosphere protects Earth from the continual fl ow of charged particles coming from the sun. These streaming particles are referred to as solar wind.46. Occasionally, large volumes of charged particles do enter the magnetosphere, causing the air to glow in a magnifi cent display of lights, referred to as an aurora.47. The aurora in the northern hemisphere is referred to as the Aurora Borealis, or northern lights.48. Another way we can see that the Earth has a magnetic fi eld is because of the way this instrument, called a compass, reacts to it.49. A compass is an instrument with a magnetized needle that is able to rotate.50. The compass needle points north.51. For this reason, compasses are helpful in guiding people in the right direction, especially if they are lost in the wilderness.52. Graphic Transition – Electricity and Magnetism53. Whenever you turn on a light,…54. ...use a computer,…55. ...or dry your hair with a blow dryer, you are using energy which magnets helped create.56. You Decide!

What is this type of energy?57. It is electricity. Did you know that electricity and magnetism are very closely related?58. Believe it or not, electricity can make magnetism and magnetism can make electricity.59. Nearly 200 years ago, scientists fi rst observed the interaction between magnets and electricity when they noticed that a compass needle moves when an electric current comes close to it.60. Scientists concluded that electric currents produce magnetic fi elds.


Video Script61.They also found that if a wire is twisted into many loops, called a solenoid, the

magnetic force produced becomes greater.62.Graphic Transition – Electromagnets63.This nail contains a high concentration of iron.64.When we wrap a wire around a nail, forming many coils,…65. ...and then pass an electric current through the wire, an amazing thing happens.66.The nail develops powerful magnetic properties.67.This is called an electromagnet.68.An electromagnet consists of a solenoid with a magnetic material, such as iron, inside

it.69.Some electromagnets, such as the one attached to this piece of machinery, are so

strong they can lift large pieces of metal. 70.This electromagnet is very useful in this scrap yard.71.Graphic Transition – Electricity from Magnets72.We just saw how electricity can produce a magnetic fi eld and an electromagnet.73.But is it possible for a magnet to produce electricity? Amazingly, it is!74.This instrument is called a galvanometer. When connected to wires, it measures

electrical current. 75.You Observe!

What happens to the needle on the galvanometer as we quickly pass a magnet into the solenoid?

76.As you can see, the needle moves, indicating that an electric current is produced.77.Electromagnetic induction is the process of generating an electric current. This

happens when a conductor, such as a wire, passes through a magnetic fi eld, in this case, the bar magnet.

78.Electromagnetic induction plays a very important role in generating the electricity we use in our homes.

79.Graphic Transition – Generating Electricity80.This device, called a generator, uses magnets and conductors to produce electricity.81.Generators convert mechanical energy into electrical energy.82.Generators produce electricity used to light our homes and operate a wide range of

electrical devices, from refrigerators,…83. ...to power tools,…84. ...to amusement park rides.85. Inside this generator are many large magnets which are spinning at a very high rate of

speed.86.The spinning magnets induce an electrical charge on the surrounding wire and

electricity is produced.87.You may be wondering what force is responsible for spinning the magnets.88.Well, in this case, water contained by this dam is diverted across a turbine, causing

the magnets to spin.


Video Script89.Other sources of fuel, such as coal and nuclear power, are used to heat water to

produce superheated steam. 90.More environmentally-friendly sources of energy, such as wind and geothermal power,

are increasingly being used as alternative energy sources.91.Graphic Transition – Summing Up92.During the past few minutes, we have explored the fascinating topic of magnets and

electromagnets.93.We began by discussing some of the characteristics of magnets, including their ability

to attract objects containing iron…94. ...and the ability of magnets to create invisible fi elds of force called magnetic fi elds.95.We also saw how Earth possesses a magnetic fi eld which infl uences devices, such as

compasses…96. ...and also plays a role in the formation of auroras.97.Electrical current has the ability to form magnetic fi elds.98. In turn, when a wire containing current is coiled around an object containing iron, an

electromagnet is formed.99.The amazing ability of magnets to create electricity was demonstrated.100. As was the ability of generators to convert mechanical energy into electrical energy through the use of magnets and conductors.101. So, the next time you use a magnet,…102. ...use a compass,…103. ...or use some electricity,…104. ...think about some of the things we’ve discussed during the past few minutes.105. You just might think about magnetism and electromagnetism a little differently.106. Graphic Transition – Video Assessment107. Fill in the correct word to complete the sentence. Good luck and let’s get started.

1. A magnet attracts materials containing ______.2. A magnetic _______ is an invisible force surrounding a magnet.3. This instrument is called a ________.4. ___________ induction is the process by which current is produced when a conductor changes a magnetic fi eld.5. A _______ converts mechanical energy into electrical energy.

Answers can be found on page 12.


Answer Key to Student AssessmentsPre-Test (p. 14-15) Post-Test (p. 16-17)

Video Review (p. 18)

1. d - north2. b - repulsion3. b - magnetic fi eld4. a - poles5. d - magnetosphere6. a - aurora7. c - compass8. d - electric current9. d - electromagnetic induction10. c - generator11. false12. false13. true14. true15. true16. Like poles repel each other and unlike poles attract each other. 17. A solenoid is a long coil of wire that produces a magnetic fi eld when current fl ows through it. 18. A compass has a magnetized needle that is able to rotate and always points north.19. Electromagnets are composed of a current-carrying wire coiled around an iron core. 20. Electromagnetic induction is the process of generating an electric current by passing a conductor through a magnetic fi eld.

1. The material is iron. 2. The magnets repel each other.3. The type of energy is electricity.4. The needle moves, indicating that an electric current is produced.

1. iron2. fi eld3. compass4. electromagnetic5. generator

1. d - electric current2. a - aurora3. b - magnetic fi eld4. d - north5. c - compass6. b - repulsion7. d - electromagnetic induction8. a - poles9. c - generator10. d - magnetosphere11. false12. true13. true14. false15. true16. Electromagnetic induction is the process of generating an electric current by passing a conductor through a magnetic fi eld. 17. Electromagnets are composed of a current-carrying wire coiled around an iron core. 18. Like poles repel each other and unlike poles attract each other. 19. A compass has a magnetized needle that is able to rotate and always points north.20. A solenoid is a long coil of wire that produces a magnetic fi eld when current fl ows through it.


In Your Own Words (p. 20)

Writing Activity (p. 20)

Vocabulary (p. 19 )

Answer Key to Student Activities

1. magnet2. magnetic poles3. magnetosphere4. repulsion5. compass6. solenoid7. electromagnet8. galvanometer9. electromagnetic induction10. generator

1. Generators use magnets and conductors to produce energy. Spinning magnets inside conductors induce an electrical charge on the surrounding wire to produce electricity.2. Examples of environmentally-friendly sources of energy include wind power, geothermal power, solar power, and hydropower.3. An electromagnet is a temporary magnet made of a current-carrying wire coiled around an iron core.

Build a Compass (p. 21)1. The needle should point north.2. If you rubbed the magnet along the needle in both directions, the needle would not become magnetized.3. The needle would be attracted to the edges of a metal bowl containing iron, rather than Earth’s magnetic fi eld.

Exploring Electromagnetism (p. 24)1. A magnetic force is created in the wire. 2. The nail was not able to pick up the paper clips. If the circuit is not closed, electric current cannot fl ow and magnetic effects will not be produced. 3. An electromagnet would not be produced because wood is not a magnetic material.

Magnetic Fields (p. 23)1. repulsion2. attraction

The Power of Water (p. 25)1. Electromagnetic induction is the process of producing electric current by moving a wire through a magnetic fi eld.2. Large-scale hydro power disrupts the lives of organisms that live upstream from dams. It causes the stream level to fl uctuate constantly and makes it diffi cult for salmon to spawn.3. Micro-hydro power does not produce pollution, is easy to install and maintain, and has little impact on the fl ow of streams. 4. Micro-hydro requires a fast-moving stream, a long pipe, and a turbine.5. A “run-of-river” system diverts stream water through a generator and then back into the stream.

Most people use magnets in their everyday lives. A magnet is a material that attracts iron, materials containing iron, and some other materials. A magnet has two poles where its magnetic effects are strongest. When two magnets come near one another, they exert a force, referred to as a magnetic force. When the north pole of one magnet comes near the north pole of another magnet, they repel, or push away from, each other. The rule of magnetic force is: like poles repel each other and unlike poles attract each other. Magnets are surrounded by an invisible force called a magnetic fi eld, which exerts a force on magnetic materials near it. Earth is surrounded by an immense magnetic fi eld. This magnetic fi eld, called the magnetosphere, protects Earth from charged particles coming from the sun, referred to as solar wind. Sometimes these particles become trapped in the magnetosphere and create a magnifi cent display of lights, referred to as an aurora.

Visual Learning Company

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14Magnets and Electromagnetism

NamePre-Test

4. Where is Earth’s magnetic fi eld the strongest?

5. The region around Earth where its magnetic fi elds are located:

1. In what direction will the north pole of a freely-fl oating magnet point?

2. What force would result if the north poles of two magnets were brought near one another?

3. The area surrounding a magnet that exerts a force on all magnetic materials located near it:

Circle the best answer for each of the following questions.

6. The northern lights are an example of a(n):

10. This device uses magnets and conductors to convert mechanical energy into electrical energy:

7. This instrument uses a magnet to help guide people in the right direction:

8. What must fl ow through a solenoid for it to produce a magnetic fi eld?

9. This is the process of generating an electric current by passing a conductor through a magnetic fi eld:

a. west b. south c. east d. north

a. attraction b. repulsion c. friction d. compaction

a. electrical fi eld b. magnetic fi eld c. magnetosphere d. magnetite

a. equator a. equator a. equator b. stratosphere c. atmosphere d. magnetosphere

a. poles b. equator b. equator b. equator c. mountain tops d. ocean fl oor

a. aurora b. conductor b. conductor b. conductor c. direct current d. electric charge

a. galvanometer b. generator b. generator b. generator c. compass d. computer

a. heat b. oil c. water c. water c. water d. electric current

a. magnetic force b. conduction c. osmosis d. electromagnetic induction

a. galvanometer b. compass c. generator c. generator c. generator d. computer


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Write a short answer for each of the following.

Pre-Test

16. Explain how like poles behave when they come near one another and how unlike poles behave when they come near one another.

17. What is a solenoid?

18. How does a compass work?

11.

12.

13.

14.

15.

Write true or false next to each statement.

19. Of what are electromagnets composed?

20. What is electromagnetic induction? How does it work?

Magnetic effects are strongest at the center of a magnet.

Like poles attract each other.

Magnetic fi elds are three dimensional.

Earth is surrounded by an immense magnetic fi eld.

Electricity can create magnetism and magnetism can create electricity.


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Circle the best answer for each of the following questions.

Post-Test

8. Where is Earth’s magnetic fi eld the strongest?

10. The region around Earth where its magnetic fi elds are located:

4. In what direction will the north pole of a freely-fl oating magnet point?

6. What force would result if the north poles of two magnets were brought near one another?

3. The area surrounding a magnet that exerts a force on all magnetic materials located near it:

2. The northern lights are an example of a(n):

9. This device uses magnets and conductors to convert mechanical energy into electrical energy:

5. This instrument uses a magnet to help guide people in the right direction:

1. What must fl ow through a solenoid for it to produce a magnetic fi eld?

7. This is the process of generating an electric current by passing a conductor through a magnetic fi eld:

a. west b. south c. east d. north

a. attraction b. repulsion c. friction d. compaction

a. electrical fi eld b. magnetic fi eld c. magnetosphere d. magnetite

a. equator a. equator a. equator b. stratosphere c. atmosphere d. magnetosphere

a. poles b. equator b. equator b. equator c. mountain tops d. ocean fl oor

a. aurora b. conductor b. conductor b. conductor c. direct current d. electric charge

a. galvanometer b. generator b. generator b. generator c. compass d. computer

a. heat b. oil c. water c. water c. water d. electric current

a. magnetic force b. conduction c. osmosis d. electromagnetic induction

a. galvanometer b. compass c. generator c. generator c. generator d. computer


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NamePost-Test

Write a short answer for each of the following.

11.

12.

13.

14.

15.

Write true or false next to each statement.

Magnetic effects are strongest at the center of a magnet.

Like poles attract each other.

Magnetic fi elds are three dimensional.

Earth is surrounded by an immense magnetic fi eld.

Electricity can create magnetism and magnetism can create electricity.

18. Explain how like poles behave when they come near one another and how unlike poles behave when they come near one another.

20. What is a solenoid?

19. How does a compass work?

17. Of what are electromagnets composed?

16. What is electromagnetic induction? How does it work?


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3. This instrument is called a ____________ .

2. A magnetic ____________ is an invisible force surrounding a magnet.

1. A magnet attracts materials containing ____________ .

4. ____________ induction is the process by which current is produced when a conductor changes a magnetic fi eld.

After you watch the video, test your knowledge with these questions.

While you watch the video, answer these questions:

Video Review

2. You Predict! What will happen when the north pole of this magnet is brought near the north pole of another magnet?

3. You Decide! What is this type of energy?

1. You Decide! What is this material?

4. You Observe! What happens to the needle on the galvanometer as we quickly pass a magnet into a solenoid?

5. A ____________ converts mechanical energy into electrical energy.


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A temporary magnet made of a current-carrying wire coiled around an iron core.

The force that occurs when the north poles of two magnets are drawn toward one another.

Vocabulary

The process of generating an electric current from a changing magnetic fi eld.

Use these words to fi ll in the blanks next to the sentences below.

A material that attracts iron or materials containing iron.

The ends of magnets where magnetic effects are strongest.

The region around Earth where magnetic fi elds are located.

An instrument that measures electrical current.

A long coil of wire that produces a magnetic fi eld when electric current fl ows through it.

1.

7.

2.

6.

8.

4.

5.

3.

An instrument with a magnetized needle that rotates to help guide people in the right direction.

9.

A device that uses magnets and conductors to produce electricity.

10.

Wo

rds

galvanometer magnet generator repulsion solenoid compass

magnetosphere electromagnet electromagnetic induction magnetic poles


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2. Give two examples of environmentally-friendly energy sources.

1. How do generators produce electricity?

Use the correct word listed above to complete the sentences in the following paragraph.

Writing Activity

Most people use magnets in their everyday lives. A ____________ is a material that

attracts iron, materials containing iron, and some other materials. A magnet has two

____________ where its magnetic effects are strongest. When two magnets come

near one another, they exert a force, referred to as a _________ _________. When the

north pole of one magnet comes near the north pole of another magnet, they ________,

or push away from, each other. The rule of magnetic force is: ____________ poles

repel each other and ____________ poles attract each other. Magnets are surrounded

by an invisible force called a _________ _________, which exerts a force on magnetic

materials near it. Earth is surrounded by an immense magnetic fi eld. This magnetic

fi eld, called the ____________, protects Earth from charged particles coming from the

sun, referred to as _________ _________. Sometimes these particles become trapped

in the magnetosphere and create a magnifi cent display of lights, referred to as

an ____________.

In Your Own Words

3. What is an electromagnet?

Wo

rds

aurora repel unlike poles magnet likesolar wind magnetic forcemagnetic force magnetospheremagnetosphere magnetic fi eldmagnetic fi eld


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NameBuild a Compass

Background: Have you ever used a compass? Perhaps you have used one to fi nd your way in the forest or have seen someone use a compass while driving on city streets. All compasses have a magnetized needle that is able to rotate. The needle lines up with Earth’s magnetic fi eld and always points north. You’re going to learn how to make a compass in this activity.

Materials: large needlenon-metal bowl cork or foamwatermagnetcompassdish soaptape

Activity: 1. Fill the bowl with water. Add a drop of dish soap. 2. To magnetize the needle, rub it several times with the magnet. Be careful to only rub it in one direction. You may need to rub the needle as many as fi fty times. 3. Push the needle through the piece of foam or thin cork. Be very careful not to prick yourself with the needle! If you do not feel comfortable doing this, ask your teacher for assistance. You may need to tape the needle to the cork if it will not easily push through it. 4. Float the cork or foam in the water. Allow it to stop moving. Note in what direction the needle is pointing.5. Test your homemade compass by comparing it with another compass. Do the needles point in the same direction?6. Answer the questions below.

Questions:1. In what direction does the needle point?

2. Step two of the activity tells you to rub the magnet in one direction. What would happen if you rubbed it in both directions?

3. Why is it necessary to use a non-metal bowl?

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NameMagnetic FieldsBackground: All magnets have two poles — a north pole and a south pole — where its magnetic effects are strongest. When two magnets are brought near one another, they exert a force on one another, referred to as magnetic force. When like poles, such as two north poles, come near one another, they repel one another. When two opposite poles come near one another, they attract each other. Magnets are also surrounded by an invisible force called a magnetic fi eld, which exerts a force on magnetic materials near it. In this activity, you will learn more about magnetic fi elds and magnetic forces.

Materials:two bar magnetshorseshoe magnetiron fi lingspiece of thin cardboard

Activity:Caution! Iron fi lings can wreak havoc on computers and other electronics. If they come in direct contact with a magnet, they will be very diffi cult to remove!The students will observe the teacher conduct this activity. The teacher will place magnets in different arrangements under a piece of cardboard that is covered with iron fi lings. Based on the arrangement of the fi lings, students will identify the type and arrangement of the magnet(s). 1. Place one bar magnet beneath the cardboard and sprinkle the iron fi lings on top. Ask students to identify the magnet and draw a diagram of it in the box labeled Diagram 1. 2. Repeat step 1 with a horseshoe magnet and ask students to draw a diagram of it in the box labeled Diagram 2.3. Place two bar magnets under the cardboard, with the north poles located near one another. Ask students to draw the outline of the magnets and to label the north and south poles on each. Have students create this sketch in the box labeled Diagram 3. 4. Repeat step 3 with the north pole of one magnet near the south pole of the other magnet. Ask students to draw the magnets in the box labeled Diagram 4.

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Questions:1. What force was exhibited in step 3?

2. What force was exhibited in step 4?

Magnetic FieldsDirections: Based on what you know about magnetic force and magnetic fi elds, identify the shape and arrangement of the magnet(s) that your teacher is using in each step. Draw an image of the magnet(s) and label the north and south poles.

Diagram 1 Diagram 2

Diagram 3 Diagram 4


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NameExploring ElectromagnetismBackground: We use electricity in many ways. For example, before coming to school today, you may have used electricity to power the alarm clock that woke you up, to turn on a light so that you could see, and to make breakfast. Did you know that electricity can produce a magnetic fi eld, as well as an actual magnet? An electromagnet is a temporary magnet created by electric current. Electromagnets consist of two parts: a solenoid and an iron core. A solenoid is a current-carrying coil of wire that produces magnetic effects. These effects are greatly enhanced when the solenoid is wrapped around an iron core, creating an electromagnet. You will make an electromagnet in this activity.

Materials:D-cell batterythin, insulated wirescissors

Activity:1. The teacher should remove, or help students safely remove, the insulation from both ends of the wire.2. Wrap the wire around the nail at least 25 times. Leave a few centimeters of free wire on both ends.3. Attach one end of the wire to the positive (+) battery terminal and the other end to the negative (-) terminal. 4. Try to pick up the paper clips with the nail.5. Disconnect both ends of the wire from the battery. Try to pick up the paper clips again. 6. Answer the questions below.

Questions:1. What force was created in the nail when both wires were attached to the battery?

2. What happened when the wire was disconnected? Why did this happen?

3. What do you think would happen if you placed a piece of wood inside the wire?

large iron nailpaper clips


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The Power of WaterGenerators produce the electricity used in most of our homes and to operate a variety of devices, including amusement park rides and power tools. Generators convert mechanical energy to electrical energy via electromagnetic induction. Electromagnetic induction is the process of producing electric current by moving a wire through a magnetic fi eld. Most generators produce electricity by rotating a coil of wire inside a magnetic fi eld. The magnets cause electrons to move, which become electric current when the generator is connected to an electric circuit. Generators rely on different sources of mechanical energy to make the magnets spin.

Many generators use nonrenewable forms of mechanical energy, such as fossil fuels. Nonrenewable energy sources harm the environment in a variety of ways, leading to different kinds of pollution and global warming. However, falling water is a powerful source of mechanical energy that has less impact on the environment. Electricity generated from water is referred to as hydroelectricity. Hydroelectricity is a form of renewable energy, which means that it can be used again and again. Many countries rely on large-scale hydro power and build immense dams to create large amounts of falling water. Dams raise the water level, causing the water to fl ow through huge pipes into a building where turbines are stored. The water causes the turbines, which are connected to generators, to spin quickly and electricity is produced. While hydro power is more environmentally-friendly than power from nonrenewable resources, it does take a toll on the environment. Building dams disrupts the lives of organisms that live near the dam. Consider the effect on fi sh. Dams often cause a constant fl uctuation in the water level, to which fi sh have a diffi cult time adjusting. Also, dams do not allow fi sh to migrate freely up and down the river. Salmon, which travel upstream to spawn, or lay their eggs, are often blocked by dams.

There is a more environmentally-friendly way to generate electricity from falling water — micro-hydro power. Micro-hydro uses a “run-of-river” system, which means that the stream water fl ows through the generator and then back to the stream with little impact on the organisms living within it. A small-scale hydroelectric generator has a small water wheel or turbine that spins when it is hit by fast-moving jets of water. Water in fast-moving streams is funneled down through a long pipe in which the water picks up speed. Nozzles direct the water to the turbine blades, causing them to spin rapidly. This turbine is connected to a generator, which produces electricity. Micro-hydro produces a smaller amount of electricity than large-scale hydro generators, but is ideal for small rural communities, particularly those located near steep streams. It is easy to install and maintain, produces no pollution, and has minimal impact on the fl ow of a stream.

Questions: 1. What is electromagnetic induction?2. How does large-scale hydro power impact the environment?3. What are the benfi ts of micro-hydro power?4. What materials are needed to produce micro-hydro power?5. What is a “run-of-river” system?

Directions: Read the information below and answer the questions that follow.

magnet.electro guide new - gvlibraries.org

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