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THE MAGIC OF MAGNETS From Electricity and Magnetism A Unit of Study Produced by Colgren Communications Written by John Colgren Distributed by... 800.323.9084 | FAX 847.328.6706 | www.unitedlearning.com This video is the exclusive property of the copyright holder. Copying, transmitting, or reproducing in any form, or by any means, without prior written permission from the copyright holder is prohibited (Title 17, U.S. Code Sections 501 and 506). © 2004 Colgren Communications Table of Contents Introduction . . . . . . . . . . . . . . . . . . . . . . .1 Instructional Notes . . . . . . . . . . . . . . . . .1 Links to Curriculum Standards . . . . . . . . .2 Student Objectives . . . . . . . . . . . . . . . . .3 Assessment Tools . . . . . . . . . . . . . . . . . . .3 Unit Test . . . . . . . . . . . . . . . . . . . . . . . . .4 Teacher Preparation . . . . . . . . . . . . . . . . .4 Introducing the Program . . . . . . . . . . . . .4 View the Program . . . . . . . . . . . . . . . . . . .4 Discussion Questions . . . . . . . . . . . . . . . .4 Description of Blackline Masters . . . . . . .5 Enrichment Activities . . . . . . . . . . . . . . . .6 Answer Key . . . . . . . . . . . . . . . . . . . . . . . .7 Internet Resources . . . . . . . . . . . . . . . . .11 Script of Narration . . . . . . . . . . . . . . . . .11 This video is closed captioned. The purchase of this program entitles the user to the right to reproduce or duplicate, in whole or in part, this teacher’s guide and the blackline master handouts that accompany it for the purpose of teaching in conjunction with this program, The Magic of Magnets. This right is restricted only for use with this program. Any reproduction or duplication in whole or in part of this guide and the blackline master handouts for any purpose other than for use with this program is prohibited. CLASSROOM/LIBRARY CLEARANCE NOTICE This program is for instructional use. The cost of each program includes public performance rights as long as no admission charge is made. Public performance rights are defined as viewing of a video in the course of face-toface teaching activities in a classroom, library, or similar setting devoted to instruction. Closed Circuit Rights are included as a part of the public performance rights as long as closed-circuit transmission is restricted to a single campus. For multiple locations, call your United Learning representative. Television/Cable/Satellite Rights are available. Call your United Learning representative for details. Duplication Rights are available if requested in large quantities. Call your United Learning representative for details. Quantity Discounts are available for large purchases. Call your United Learning representative for information and pricing. Discounts, and some special services, are not applicable outside the United States. Your suggestions and recommendations are welcome. Feel free at any time to call United Learning at 1-800-323-9084. THE MAGIC OF MAGNETS from Electricity and Magnetism A Unit of Study Grade Levels: 5-8 Viewing Time: 15 minutes INTRODUCTION This live-action program is designed for use with the intermediate grade levels (5-8). This program is about magnetism. Magnetism was probably discovered by accident when a farmer, or herder, from ancient Greece came across a natural magnet called magnetite. Possibly his metal spear was attracted to this rock. This unusual effect was discovered in a part of Turkey called Magnesia, so the Greeks called the rock magnetite. There are all kinds of magnets and they are used in a wide variety of ways—from holding messages on refrigerator doors to generating electrical power at the local power station. This program explores magnets from their many uses to how certain metals can be made into magnets. INSTRUCTIONAL NOTES Before presenting this lesson to your students, we suggest that you preview the program and review this guide and the accompanying blackline master activities in order to familiarize yourself with their content. As you review the materials presented in this guide, you may find it necessary to make some changes, additions, or deletions to meet the specific needs of your class. We encourage you to do so, for only by tailoring this program to your class will they obtain the maximum instructional benefits afforded by the materials. It is also suggested that the program presentation take place before the entire group under your supervision. The lesson activities grow out of the context of the program; therefore, the presentation should be a common experience for all students. 1 LINKS TO CURRICULUM STANDARDS This Unit of Study addresses the following National Science Education Standards for grades 5-8: Science as Inquiry Content Standard A: • Abilities necessary to do scientific inquiry Plan and conduct simple investigations. Employ simple equipment and tools to gather data. Use data to construct a reasonable explanation. Communicate investigations and explanations. • Understanding about scientific inquiry Physical Science Content Standard B: • Energy is a property of many substances and is associated with heat, light, electricity, mechanical motion, sound, nuclei, and the nature of a chemical. Energy is transferred in many ways. • Electrical circuits provide a means of transferring electrical energy when heat, light, sound, and chemical changes are produced. Science and Technology Content Standard E: • Abilities of technological design • Understanding about science and technology People have always had questions about their world. Science is one way of answering questions and explaining the natural world. People have always had problems and invented tools and techniques to solve problems. Scientists and engineers often work in teams. Tools help scientists make better observations, measurements, and equipment for investigations. History and Nature of Science Content Standard G: • Science as a human endeavor Science and technology have been practiced for a long time. Men and women have made a variety of contributions throughout the history of science and technology. 2 Although men and women using scientific inquiry have learned much about the objects, events, and phenomena in nature, much more remains to be understood. Science will never be finished. Many people choose science as a career and devote their entire lives to studying it. STUDENT OBJECTIVES After viewing the program and participating in the lesson activities, the students should be able to do the following: • Describe the differences between permanent and electromagnets. • Describe how an electromagnet is made and operated. • Describe ways a permanent magnet can be damaged. • Define the terms attract and repel with regard to the way magnets affect each other. • Identify the poles of a magnet as the most powerful parts of the magnet. • Describe uses of permanent and electromagnets. ASSESSMENT TOOLS This lesson provides you with three different assessment tools. Together they make it possible to closely follow the progress of your students and to judge their mastery of the subject matter. The Pre-Test (Blackline Master 1) can be used to get some idea of students' understanding of the topic before the program is presented. The Program Quiz and its accompanying answer sheet (Blackline Master 2) can be used either as a way to introduce the topic prior to showing the program or to judge student mastery once the program has been presented. The Post-Test (Blackline Master 13) can be used as a final test for the lesson. 3 UNIT TEST An optional Unit Test has been provided with this lesson. It can be used as a final test to gauge student comprehension of the material presented in all five lessons of this Unit of Study. Answers to the Unit Test are provided in the Answer Key of this instructor’s guide. TEACHER PREPARATION View the program and review the accompanying activities. Duplicate any blackline masters you wish to distribute. If you plan to use the Program Quiz, which immediately follows the program presentation, you may wish to have copies of the quiz ready to distribute at the completion of the program. Also, plan to pause the tape between questions if students require more time. INTRODUCING THE PROGRAM Ask the students to help you list some uses of magnets. The list should include things such as holding things on refrigerators, novelty toys or desk displays, clasps for jewelry, and other common uses. However, magnets help our phones to work. In every phone, there is a magnet that helps change the electrical signals into sound waves. Magnets are a part of electric motors. Magnets help guide the electron guns shooting electrons at our television screens so that we can see our favorite shows. Probably the most important job magnets have is in the production of electricity in the giant generators at power plants. VIEW THE PROGRAM Viewing time for this program is 15 minutes. The program quiz that follows the presentation will take about three minutes when you build in pauses for recording answers. DISCUSSION QUESTIONS You may wish to conduct a discussion after viewing the program based on the following: 1. Review with the class the procedures for turning an iron nail 4 into a magnet. Why do we have to stroke the nail repeatedly in the same direction with a permanent magnet? (The atoms of the iron nail need to be magnetically aligned). Why would dropping the nail or heating the nail cause the magnetism to be lost? (Dropping the nail would cause the atoms to become jostled and out of alignment. Heating the nail causes the atoms to move faster and fall out of alignment). 2. What are some advantages of the maglev train? Non-polluting; high speeds of 300 miles per hour; quiet, smooth ride. DESCRIPTION OF BLACKLINE MASTERS This program contains 13 blackline masters that can be used to reinforce ideas and information presented in the program. • Blackline Master 1, Pre-Test, provides a way of finding out how much students know about the material covered in this lesson before you present it. Students’ scores on the Pre-Test can be compared with their scores on the final Post-Test (Blackline Master 13). • Blackline Master 2, Program Quiz, is to be used at the end of the program. At the completion of the program, there is a short quiz. The narrator will read the questions which are displayed on the screen. Students can use Blackline Master 2 to record their answers. Answers to the questions are provided in the Answer Key section of this instructor's guide. • Blackline Master 3, Compass Construction, is an experiment designed to demonstrate how the early Chinese sailors constructed a compass for navigating a ship at sea. • Blackline Master 4, What Do Magnets Attract?, is an experiment to test different objects and determine whether they are attracted by a magnet or not. • Blackline Master 5, Lines of Force, is an experiment for observing the lines of force between two different magnets as the like and opposite poles are brought closer to each other. 5 • Blackline Master 6, Cut Up, is an experiment to illustrate what happens when a magnet is cut into pieces. • Blackline Master 7, Don't Do It, is an experiment to demonstrate what happens when a magnet is dropped or heated. Students will make magnets out of some small iron nails. • Blackline Master 8, Magnetism from Electricity, demonstrates that electricity produces magnetism. This is similar to the classic demonstration of 1820 by the Danish physicist, Hans Oersted. • Blackline Master 9, Electricity from Magnetism, is an experiment that demonstrates the famous experiment by Michael Faraday, which shows how a bar magnet moving in and out of a coil of wire will create a flow of electrons. • Blackline Master 10, Electromagnets, asks students to build an electromagnet and then test it with paper clips. At the bottom of the page are some ideas for further investigation. • Blackline Master 11, Maglev, is an experiment for constructing a maglev demonstration. • Blackline Master 12, Maglev, Version 2, is another method for illustrating magnetic levitation. This one is very cool because if it is set up properly, you can spin the pencil and it will almost magically hover in place for quite a while. • Blackline Master 12, Post-Test, is an evaluation tool for this unit. ENRICHMENT ACTIVITIES 1. Have some interested students do more research into maglev trains. So far, the countries of Germany and Japan have led the way in this new technology. In the United States, there are a few projects that are planned to begin in the next few years. There is a test facility in Florida. 2. Have students write a paper that discusses the advantages of a mass transit system that utilizes the technology of magnetic 6 levitation. Have them consider the advantages of high speed and no pollution. Wouldn't such a system pay for itself within a short period of time? Imagine all the people who would want to ride on such a network simply because it is such a novelty. ANSWER KEY • Blackline Master 1, Pre-Test I. Fill in the blank 1. electricity 2. poles 3. repel 4. attract 5. iron, nickel, or cobalt II. Short Answer 1. To make an electromagnet, you need an iron nail, some wire, and a dry cell. Wrap the wire around the nail, leaving a few inches of wire at each end to connect to the dry cell. The more wraps, the strong the magnetic force. 2. An electromagnet can be turned on and off. That means you can control the magnetism of an electromagnet. You can't do that with a permanent magnet. 3. Electromagnets are used in motors, doorbells, telephone receivers, maglev trains, etc. 4. If the same poles of two magnets are facing each other, the magnets will repel, or move away, from each other. Like poles repel and unlike poles attract. 5. If one magnet is flipped around so that opposite poles are facing each other, then the magnets will attract. Unlike poles attract. • Blackline Master 2, Program Quiz 1. b 2. a 3. c 4. a 5. d • Blackline Master 3, Compass Construction Observations: 1. The cork and needle should spin around to be oriented with the earth's magnetic poles. 7 2. The cork and needle should realign with the earth's magnetic poles. Conclusions: 1. The needle has been magnetized, so it will now respond to the earth's magnetic poles. • Blackline Master 4, What Do Magnets Attract? Answers will vary depending on the objects selected to be tested. However, only things made of iron, nickel, and cobalt will be attracted to a magnet. • Blackline Master 5, Lines of Force • Blackline Master 6, Cut Up Observations: 1. It should have become magnetic. 2. Yes 3. Yes Conclusion: A magnet can be cut into smaller pieces and still retain its magnetism. • Blackline Master 7, Don't Do It Observations: 1. Yes 2. No 3. No Conclusion: Dropping and heating will cause a magnet to lose its magnetism. • Blackline Master 8, Magnetism from Electricity Observations: 1. The compass needle will begin to spin. 2. The needle of the compass would stop spinning. 8 Conclusions: 1. It demonstrates that electricity causes a magnetized needle to respond and spin. This means that the electricity is producing a magnetic field in the coil of wire. 2. If more wire is used, there will be more of an effect. • Blackline Master 9, Electricity from Magnetism The compass needle will move as the magnetic bar is drawn in and out of the coil of wire. If you watch closely, you will see that the needle moves one way when the magnetic bar goes in the coil and the needle moves the opposite way when the magnetic bar is moved out of the coil of wire. This is called alternating current. • Blackline Master 10, Electromagnets 1. No 2. Yes 3. The magnetism stops and the paper clips fall. Conclusions: The electromagnet only works when electricity is flowing through it. When the electricity is turned off, the electromagnet loses its magnetic force. • Blackline Master 11, Maglev It bounces back up. • Blackline Master 12, Maglev Version 2 When the pencil is given a spin, it will turn quickly as it hovers over the magnets. There is very little friction in this set-up because the only thing making contact is the pencil tip on the smooth surface of glass. The pencil will spin for quite awhile. • Blackline Master 13, Post-Test Definitions: 1. Repel means to move away from or force away. 2. Attract means to come together or pull towards each other. 3. An electromagnet is a magnet that only works when electricity is flowing through it. Its magnetism can be controlled. 4. The poles of a magnet are the opposite ends of the magnet. They are the most powerful parts of the magnet. 5. Magnetite is a natural stone that has magnetic properties. 9 II. Short answer 1. Wrap wire around an iron nail and then connect the ends of the wire to a dry cell. 2. Electromagnets are used in motors, doorbells, telephones, magnetic levitation trains, etc. 3. Electromagnets can be controlled. Their magnetism can be turned on and off. Permanent magnets can't be turned on and off. 4. A magnet spinning inside a coil of wire or a coil of wire spinning inside a magnetic field will cause electricity to flow. 5. Bring a compass near a wire that has electricity flowing through it and the needle will move around. • Unit Test I. Matching 1. d 2. h 3. f 4. a 5. i 6. g 7. c 8. e 9. b II. Short Answer 1. copper, silver, gold 2. wood, glass, rubber, cloth, plastic 3. Insulators are used to stop the flow of electricity. In-sulators around a wire will stop the electricity from moving out of the wire and into another conductor. 4. A generator produces electricity. It is made of either a coil of wire spinning in a magnetic field or a magnet spinning in a coil of wire. In either case, a flow of electrons is created. 5. An electromagnet can be made with a source of electrons, some wire, and an iron nail. Wrap the wire around the nail. Connect the wire ends to the terminals of the battery and you have an electromagnet. 6. An electromagnet can be turned on and off, but a regular bar magnet can't. 7. A source of electrons, a path for the electrons to flow along, and something to use the electrons. 8. battery battery 10 9. A series circuit has one path on which electricity flows. If a bulb in a series circuit burns out, all the lights go out. A parallel circuit has two paths on which the electricity flows. If one bulb burns out, there is still a path for the electricity to flow along so other bulbs in the circuit stay lit. 10. Fuses and circuit breakers will automatically trip, or stop, the flow of electricity if the circuit becomes overloaded by the flow of current. 11. Answers will vary. 12. The sun's energy through the use of solar cells, wind turbines, geothermal energy, chemical energy. 13. They would move apart because they would be repelled. 14. They would come together because they are attracted. 15. a. 4 amps b. 8 amps c. 6 amps INTERNET RESOURCES The following websites may be valuable sources of additional information to reinforce the objectives of this lesson: 1. http://www.school-for champions.com/science/magnetism.htm 2. Canada Science and Technology Museum http://www.sciencetech.technomuses.ca/english/schoolzone/Info _magnets.cfm SCRIPT OF NARRATION Look. Nails hanging from a rock. Paperclips picked up by a piece of rock. What’s going on here? Well, you are seeing a natural occurring magnet called magnetite or a lodestone in action. These rocks have the ability to attract certain objects with an invisible force called magnetism. It is thought that possibly two thousand years ago some ancient Greeks discovered by accident the ability of certain rocks to attract some metals. Maybe a farmer had a metal tool or spear head magically stick to a piece of magnetite. 11 They discovered this unusual effect in a part of Turkey called Magnesia, so the Greeks called the rock responsible for this attractive force magnetite. Today we have permanent magnets that are used in hundreds of ways, from holding pictures on the refrigerator to producing electricity inside huge generators. It’s fun to mess around with magnets. They come in all kinds of sizes, shapes, and strengths. Some magnets are round, some are bar-shaped, some are shaped like horseshoes, and some are donut shaped. Magnets have two poles: a north and a south pole. Sometimes the magnet is colored to distinguish from north and south. These donut magnets are an excellent way to show how magnets attract and repel. When opposite sides of the magnets are facing each other, the magnets are attracted and come together. If the similar sides are facing each other, then the magnets repel, or push away, from each other. We can illustrate this with bar magnets as well. When the same sides are brought near, they push apart. However, when opposite sides are near, they attract or pull together. Magnets don’t attract all objects. You can experiment with various objects to see what is attracted and what isn’t attracted to a magnet. It might appear that objects made of metals are all attracted but that isn’t necessarily true. Only certain metals are attracted by magnets. These coins are made of metal but are not attracted to the magnet. But this paper clip and these staples are definitely attracted to the magnet. You’ll find that only metals made of nickel, iron, and cobalt are attracted by magnets. Magnetism can penetrate objects as demonstrated by this magnet moving the paper clip through the wood. 12 If we put a bar magnet into a bowl of paperclips, we will find that most of the clips attach to the ends of the magnet. The magnets are strongest at the ends. We can see the lines of force around a magnet by placing a piece of glass or thin cardboard on top of the magnet. Then we sprinkle iron fillings onto the glass or cardboard and the little bits of iron line up along the invisible lines of force that are found around the magnet. We can view the lines of force created when the ends of two different magnets are brought near each other. Remember that unlike ends of magnets attract each other and like ends repel. Let’s look at the lines of force when unlike sides of two magnets are brought near. Now let’s turn one magnet around so that like ends are facing each other. You can see the lines of force are repelling each other. If we tie a string to a bar magnet and let it hang, it will rotate around until one end is pointing north and the other end is pointing south. The end of the magnet that points north is called the magnet’s north pole and the opposite end is called the south pole. The magnet lines up this way because the earth is a giant magnet. It is as if a giant bar magnet went through the center of the earth, as shown in this picture. The magnet isn’t really there. In fact, scientists believe that the magnetic effect is caused by very hot liquid metals in the outer core of the earth, creating electrical charges that cause a magnetic field to develop. The invisible magnetic field extends out into space, protecting the earth against solar particles released constantly by the sun. This stream of particles is called the solar wind. These charged particles make contact with the earth’s magnetic field lines and travel towards the poles. As the particles make contact with oxygen and nitrogen atoms in the atmosphere, a beautiful show of lights in the sky is displayed. These are referred to as auroras or the northern and southern lights. The ancient Chinese were the first navigators to use magnets to help them sail the seas. They found that they could use natural magnets held by string as a method for identifying north and 13 south. These were the first compasses. Later, it was discovered that a needle, or thin piece of iron, could be turned into a magnet by stroking the magnetite across it repeatedly. This needle suspended on a piece of bamboo, or cork, and floating in water would rotate around until one end pointed north. Sailors could then determine what direction they were sailing in by comparing this needle with the direction of the boat. WHAT MAKES CERTAIN MATERIALS MAGNETIC? All matter is made up of atoms. Inside atoms are orbiting electrons that speed around the atom’s center, or nucleus. The movement of electrons causes a magnetic effect and atoms develop a north and south pole. In most materials, the magnetic fields cancel each other out, so these materials have no magnetism. However, the atoms of iron, nickel, and cobalt are different. They have domains, or groups of atoms, that line up together creating a magnetic field. Objects made of iron, nickel, or cobalt can be magnetized by stroking them with a magnet. You must stroke them in the same direction to get the atoms to align properly. A magnet made this way is called a temporary magnet. This iron nail is turned into a temporary magnet after repeatedly rubbing a permanent magnet along its length. It attracts the staples because the magnetic force in the nail causes the atoms of the staples to slightly line up with the nail’s magnetic field. This creates a temporary magnetic effect in the staples and they are attracted to the nail. When the staples are knocked free, they loose that magnetic effect. Magnets can be damaged and loose their magnetic ability if they are dropped or heated. Dropping causes the domains in the atoms to be jumbled around. They fall out of alignment and the magnetic effect is lost. Heating can also damage a magnet. When atoms are heated, they move faster and, as a result, move out of alignment. ELECTROMAGNETS In 1820, the Danish physicist Hans Oersted discovered that electricity could cause a magnetic effect. During a demonstra14 tion he brought a compass near a wire that had an electric current flowing through it. The needle spun in a new direction. He found this to be very unusual, as compass needles always pointed north and south. With further experimentation, he found that electricity flowing through a wire created a magnetic effect. An electromagnet can be made with some simple materials. An iron nail, some wire, and a battery can be used to make an electromagnet. Wind the wire around the nail. Attach the ends of the wire to the battery and the electricity flowing through the wire creates a magnetic field around the wire and nail. The domains of the atoms in the nail are temporarily lined up to form a temporary magnet. When one of the ends of the wire is disconnected, the flow of electrons stops and the magnetism stops. Electromagnets are used in various ways. Doorbells use electromagnets. Notice the coiled wires and the way they attract the doorbell clapper when the electricity is applied. There are electromagnets in a phone receiver that change the electric signals into sound waves. There are electromagnets in many motors. This motor has magnets with a driveshaft between them that contains the electromagnets. Here is an experiment conducted at the Museum of Science in Boston to illustrate the power of an electromagnet. The power drill has been set up with a handle, or crank, in its bit. The batteries are removed and instead, wires are attached from the drill motor to a light bulb and to the coil of wire of an electromagnet. Using the crank, the electric motor becomes a generator as demonstrated by the light bulb. You could run a series of experiments to test what factors effect the strength of the electromagnet. Does the size of the iron core effect the strength? How about the number of turns of wire? Or maybe the strength, or voltage, of the battery used will determine the strength of the electromagnet. Set up an experiment to test all these variables one at a time. 15 ELECTRICITY FROM MAGNETISM After Hans Oersted discovered that electricity created a magnetic effect, other scientists wondered if magnetism could create electricity. In 1831, Michael Faraday, an English scientist, set up an experiment that proved that electricity could be produced when a magnet was pushed in and out of a coil of wire. Notice that the needle, which illustrates the flow of electricity, only moves when the magnet first moves. Also, notice that the needle changes direction as the magnet moves in different directions in and out of the coil of wire. Electricity produced in this fashion by a changing magnetic field is called electromagnetic induction. Faraday found that a greater electric current is induced if there are more coils of wire. He also found that if the magnet moves faster, the induced electric current is stronger. Faraday also discovered that it didn’t matter if the magnet was moved inside a coil of wire, or a coil of wire moved inside a magnetic field. In either situation, electric current is induced. At power plants, they use electromagnetic induction to produce electric current. In most large generators, a giant magnet is turned inside a coil of wire. Remember that the current electricity produced in this fashion changes direction continuously. This is called ac or alternating current. A battery produces dc or direct current. Direct current flows steadily in one direction. MAGLEV This train is traveling 355 kilometers per hour, or 220 miles per hour. That speed might seem impossible for a train but that isn’t the most exciting thing about this train. You see this train is traveling because of electricity and magnetism. This is a maglev train. Maglev stands for magnetic levitation. As you know, opposite ends of a magnet attract and similar sides repel. This train is making use of these facts to race down the track. This is the German magnetic levitation train called “transrapid.” It is designed to go as fast as 550 kilometers per hour, which is 342 miles per hour. There are magnetized coils run16 ning along the track, or guideway. On the underside of the train are large magnets. When electricity flows into the guideway coils, a magnetic field develops. The opposing magnetic fields of the guideway and train lift, or levitate, the train about one centimeter, or about one third of an inch, above the track. Once levitated, the electromagnet coils in the guideway are used to push and pull the train along on a cushion of air. Because the train is floating, there is no friction between the train and track, which allows the train to reach unbelievable ground transportation speeds. This form of transportation has been in development since the 1970s. Look at this maglev demonstration model. The device is easily suspended in mid air because inside are two donut magnets that are repelled by magnets in the base. With a little twist, the device spins effortlessly. There is only one place where contact is made, so the friction is minimal. That’s why the device spins for such a long time. With little friction between the moving parts, the device can continue to spin for long periods of time. Now it is time for the program quiz. There are five multiple choice questions. 1. If two magnets have opposite poles facing each other, they will be ________. a. repelled b. attracted c. neutralized d. opposed 2. If two magnets have the same poles facing each other, they will be _________ . a. repelled b. attracted c. neutralized d. opposed 3. ___________ are controlled by electricity. a. lodestones b. pieces pf magnetite c. electromagnets d. permanent magnets 17 4. Iron nails can be made into magnets because of their ___________. a. domains b. lodestones c. magnetite d. protons 5. Mangets are used in electric motors and __________ . a. horseshoes b. lodestones c. turbines d. generators 18 1 P R E T E S T Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism I. Directions: Fill in the blanks to complete the following statements. 1. Magnetism and ____________________ are related. 2. The ends of a magnet are called _____________. 3. When two magnets are brought close to each other and they try to move apart, we say the two magnets ____________ each other. 4. If two magnets come together, we say they _________ each other. 5. Magnets will not pick up all metals. They respond mainly to metals that have ___________ or _________ in them. II. Directions: The following questions require a short answer. 1. How can you make an electromagnet? 2. What can be done with an electromagnet that can't be done with a regular magnet? 3. Describe some ways electromagnets are used. 4. If we brought two magnets together, what would you expect to happen if the same poles are facing each other? 5. If we flip one of the magnets around and bring them together, what will happen? © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 2 P R O G R A M Q U I Z Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism Directions: At the end of the program, there is a short quiz. You can record your answers on this sheet. 1. If two magnets have opposite poles facing each other, they will be ________. a. repelled b. attracted c. neutralized d. opposed 2. If two magnets have the same poles facing each other, they will be ________. a. repelled b. attracted c. neutralized d. opposed 3. __________ are controlled by electricity. a. Lodestones b. Pieces of magnetite c. Electromagnets d. Permanent magnets 4. Iron nails can be made into magnets because of their __________. a. domains b. lodestones c. magnetite d. protons 5. Magnets are used in electric motors and __________. a. horseshoes b. lodestones c. turbines d. generators © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 3 C O M P A S S C O N S T R U C T I O N Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism Purpose: To build your own compass. Materials: bar magnet sewing needle flat cork saucer of water tape Procedures: 1. Turn the sewing needle into a magnet by stroking it across a bar magnet. Stroke it in only one direction and on only one pole of the magnet. At the end of a stroke, lift the needle off of the magnet and bring it back to the starting point. Stroke the needle across the magnet at least 40 times. 2. Tape the magnetized needle to one of the flat sides of the cork. 3. Pour water into the saucer. 4. Float the cork in the water with the needle on top. 5. Give the cork a spin and make observations. Repeat. Observations: 1. What happened when you first placed the cork and needle in the saucer of water? 2. What happened when you spun the cork and needle? Conclusions: 1. Why did the needle and cork behave as they did? © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 4 W H A T Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism Directions: Set up an experiment to find out what magnets attract. Use the chart below to record your findings. Objects tested 1. _________________________________________________________ 2. _________________________________________________________ 3. _________________________________________________________ 4. _________________________________________________________ 5. _________________________________________________________ 6. _________________________________________________________ 7. _________________________________________________________ 8. _________________________________________________________ 9. _________________________________________________________ 10. _________________________________________________________ D O M A G N E T S A T T R A C T ? Did the magnet attract it? Yes No Questions: Which things were attracted to the magnet? How are these things different from the others you tested? © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 5 L I N E S Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism Purpose: To see the lines of magnetic force that exist in a magnetic field. Materials: two bar magnets marked with N and S poles a piece of glass at least 6" by 6" iron filings two identical-sized books Procedures: 1. Set the two books so that there is a space of at least four inches between them. 2. Place the sheet of glass on the books so that the books become a support. 3. Move the two magnets under the supported sheet of glass and between the books. The magnets should be placed so that the N pole of one magnet is facing the S pole of the other magnet. 4. Sprinkle iron filings on the top of the glass and make observations. 5. Repeat this experiment; but this time, have identical poles facing each other. O F F O R C E Observations: Draw what you observed from Procedures 4 and 5 above. Conclusion: What do the lines of filings tell you about the invisible magnetic lines of force? © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 6 C U T U P Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism Purpose: To determine what happens when a bar magnet is cut into pieces. Materials: strong bar magnet a thin piece of iron wire cutters paper clips or iron filings Procedures: 1. You can make the piece of iron magnetic by stroking it many times across one of the poles of the magnet. Stroke it in one direction only. After each stroke, lift the iron off the magnet and bring it back for the next stroke. Repeat this for more than 20 times. 2. Bring the piece of iron close to paper clips or iron filings and make observations. 3. Use the wire cutters to cut the piece of iron in half. 4. Test each half to see if the magnetism remains. Make observations next to question 2 below. 5. Cut one of the halves in half and test the new pieces for magnetism. Make observations next to question 3 below. Observations: 1. Was the original piece of iron made magnetic by stroking it with a bar magnet? 2. Did each half of the cut piece of iron still have a magnetic attraction? 3. Did the small pieces of iron still have magnetism? Conclusion: What happens when a magnet is cut into smaller pieces? © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 7 Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism D O N ’ T Purpose: To demonstrate why a magnet should never be dropped or heated. Materials: strong bar magnet two iron nails candle and matches paper clips towel pliers D O Procedures: 1. You can make each nail magnetic by stroking it many times across one of the poles of the magnet. Stroke it in one direction only. After each stroke, lift the nail off of the magnet and bring it back for the next stroke. Repeat this for more than 20 times. 2. Test the attracting ability of the two nails by bringing each nail to a pile of paper clips. Make observations. If they are not strong, repeat Procedure 1. 3. Drop one of the nails on the floor. Test it for magnetism and make observations. 4. Light the candle and put the remaining nail in the pliers. Hold the pliers with the towel so your fingers aren't burned when you put the end of the nail in the candle flame. 5. Let the nail stay in the flame for a few minutes and then test its magnetic ability. (Don't touch the hot nail - use the pliers.) Make observations. I T Observations: 1. Were the two nails magnetized? 2. Was the dropped nail still magnetic? 3. Was the heated nail magnetic? Conclusion: What are the two ways a magnet could lose its magnetism? © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 8 M A G N E T I S M F R O M Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism Purpose: To demonstrate that an electric current produces magnetic fields of force. Materials: compass nine-volt battery insulated wire Procedures: 1. 2. 3. 4. Remove about one inch of insulation from the ends of the wire. Curve the wire out into a large circle. Connect it to the nine-volt dry cell. Move the compass to different points along the wire. Observations: 1. What happens to the compass needle as it is brought near the wire? 2. What happens when the dry cell is disconnected? Conclusion: What does this illustrate about the connection between electricity and magnetism? E L E C T R I C I T Y What if the wire were coiled around a toilet tissue tube? What if a shorter or longer piece of wire was used? © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 9 E L E C T R I C I T Y Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism Purpose: To demonstrate that an electric current can be generated from magnetism. Materials: compass bar magnet 25 feet of insulated wire toilet tissue tube Procedures: 1. Cut the insulated wire in half. 2. Make an electric current detector by wrapping a compass with many turns of insulated wire. 3. Wrap the other wire around the toilet tissue tube. 4. Remove the tube so that you have a nice coil of wire. 5. Remove the insulation from the ends of this wire. 6. Connect the compass wire to the toilet tissue tube wire as illustrated here. 7. Move the bar magnet in and out of the coil of wire. F R O M M A G N E T I S M Observations: 1. What did the compass needle do when you moved the bar magnet back and forth in the coil of wire? © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 10 E L E C T R O M A G N E T S Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism Purpose: To construct a working electromagnet. Materials: iron nail about three inches long 1-1/2 volt dry cell insulated wire paper clips Procedures: 1. Wrap the insulated wire around the iron nail with as many turns as you can. Be sure to leave wire on the ends to allow a hookup with the dry cell. 2. Remove about one inch of insulation from the ends of the wire. Bring the nail and wire close to a pile of paper clips. Make observations. Write an answer for Observation 1. 3. Attach the ends of the wire to the dry cell and repeat Procedure 2. Make observations. Write an answer for Observation 2. 4. Disconnect the dry cell and make observations. Write an answer for Observation 3. Observations: 1. Are the nail and wire magnetic? 2. When connected to the dry cell, did the iron nail attract or pick up paper clips? 3. What happened to the magnetism of the nail when the dry cell was disconnected? Conclusion: Under what conditions will an electromagnet pick up things made of iron? Things to try: What would happen if there were fewer turns of wire? What about more turns of wire? What if you add a stronger dry cell or more than one dry cell? © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 11 M A G L E V Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism Purpose: To demonstrate the main idea of magnetic levitation. Materials: two bar magnets the same size and shape scotch tape pen Procedures: 1. Place one magnet on a flat surface. 2. Line up the second magnet so its north side is above the north side of the first magnet. 3. Put a pen between the magnets. 4. Tape the sides of the magnets as illustrated. 5. Remove the pen. Observations: What happens when you push down on the top magnet? © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 12 M A G L E V V E R S I O N Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism Purpose: To demonstrate the main idea of magnetic levitation. Materials: pencil masking tape six round donut magnets clay microscope slide wood base and wood block Procedures: 1. Tape the glass microscope slide to the block of wood for support. 2. Put the pencil through the center holes of two donut magnets using masking tape to provide a snug fit. 3. Use clay to support the four additional donut magnets as shown in the picture below. 4. Rest the pencil point against the glass microscope slide. 5. Adjust the magnets on the pencil so that they are positioned above the four magnets on the wood base. T W O Observations: What happens when you spin the pencil? © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 13 P O S T T E S T Name ____________________ THE MAGIC OF MAGNETS from the series Electricity and Magnetism I. Directions: Define these terms. 1. repel ______________________________________________________________________ 2. attract _____________________________________________________________________ 3. electromagnet ______________________________________________________________ 4. poles of a magnet ___________________________________________________________ 5. magnetite __________________________________________________________________ II. Directions: Answer the following questions with short answers. 1. How can an electromagnet be made? 2. What are some ways electromagnets are used? 3. What makes electromagnets different from permanent magnets? 4. How can magnetism be used to produce electricity? 5. How can we demonstrate that electricity produces a magnetic effect? © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. Name ____________________ ELECTRICITY AND MAGNETISM Unit Test I. Directions: Pick the definition in column B that best matches the word in column A. Write the letter of the definition on the blank line. Column B Column A 1. electricity ________ a. When two objects come toward each other. 2. conductor ________ b. The Greek philosopher who named electricity. 3. insulator _________ c. A positively charged particle found in the nucleus of an atom. 4. attract __________ 5. repel __________ d. The flow of electrons. 6. electron _______ e. An atomic particle found in the center of an atom. It has no charge. 7. proton _______ f. Material that will not allow the flow of electricity. 8. neutron _______ g. A particle found orbiting around the nucleus of an atom. It has a negative charge. 9. Thales _______ h. Material that allows electricity to go easily through it i. When two objects move apart. II. Directions: Answer the following questions in the space provided. 1. Name three good conductors of electricity. 2. Name three good insulators. 3. Describe some uses for insulators. 4. How does a generator work? 5. Describe how a simple electromagnet could be made. 6. How is an electromagnet different from a regular bar magnet? 7. What three things are needed for a complete circuit? 8. There are two kinds of circuits: series and parallel. Finish the drawings below by adding wires. series battery battery © 2004 Colgren Communications parallel Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. Name ____________________ ELECTRICITY AND MAGNETISM Unit Test (Page 2) 9. What are the differences between a series circuit and a parallel circuit? 10. How do fuses or circuit breakers help protect homes? 11. Mechanical energy of the spinning turbine and generator produce electrical energy at a power station. Give some examples of electrical energy being changed to other forms of energy around your home. 12. Fossil fuels (oil, coal, and natural gas) are the main sources of fuels used to power the electric plants of today. What are some other sources of energy that can be used to make electricity? 13. If these two magnets were to be brought near each other, how would the lines of force look? S N N S 14. If one of the magnets was flipped over, how would the lines of force be changed? S N S N 15. Amperage is equal to wattage divided by voltage. Calculate the number of amps for each of these electrical appliances. a. electric toothbrush 480 watts 120 volts _____ amps b. electric blender 960 watts 120 volts _____amps c. microwave 720 watts 120 volts _____amps © 2004 Colgren Communications Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution.