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1 TO GO TO ANY OF THE PAGES LISTED BELOW, CLICK ON ITS TITLE CHAPTER 21 Magnetism What is a magnet? What causes magnetism? 3 Human Magnetic Fields Enrichment Activity for Lesson How can you make a magnet? How is Earth like a magnet? 6 Magnetic Variation Enrichment Activity for Lesson How are electricity and magnetism related? What is an electromagnet? 9 Electromagnetism Enrichment Activity for Lesson What is a transformer? What is an electric motor? What is an electric generator? 13 Generators Enrichment Activity for Lesson THE BIG IDEA Integrating Technology: How does a maglev train work? 15 Chapter 21 Key Term Review 16 Chapter 21 Test 17 Chapter 21 Answer Key 20 (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 1

2 21-1 What is a magnet? Determine if each item listed will be attracted to a magnet or not affected by a magnet. Write attracted or not affected in the spaces provided. 1. wooden chair 2. iron kettle 3. paper clip 4. milk carton 5. glass jar 6. refrigerator 7. bar of cobalt 8. nickel coin 9. metal filing cabinet 10. window glass Skills: analyzing, diagramming, identifying Complete the following. 1. Draw two magnets that are repelling each other. Be sure to label the poles of the magnets. 2. Draw two magnets that are attracting each other. Be sure to label the poles of each magnet. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 2

3 21-2 What causes magnetism? Use the diagram to answer the following questions. 1. What do the lines around the magnet represent? 2. What is the pattern made by the lines called? 3. Where is this magnet the strongest? 4. Where are the lines closest together? 5. What do the letters N and S stand for? Skills: interpreting diagrams, analyzing Are the poles of the magnets in the following diagrams attracting or repelling each other? Write attracting or repelling in the space provided below each diagram. Then, draw the magnetic lines of force between the poles of each magnet. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 3

4 Human Magnetic Fields Enrichment Activity for Lesson 21-2 Skills: inferring, relating The following passage describes a recent breakthrough in medical technology. Read the passage. Then, answer the questions. Organs in the human body have magnetic fields, just as Earth or a horseshoe magnet has a magnetic field. The most common source of magnetism in the body is electric currents generated naturally by muscles and nerves. The heart and brain produce the most current. New technology has provided better detectors for the tiny magnetic fields produced by organs. One of the newest and most sensitive detectors is known as SQUID. This name stands for Superconducting Quantum Interference Device. Much of the research done with SQUID on human magnetism is centered on the brain. Electric currents in the brain produce magnetic fields. When these fields are sensed by SQUID, they produce charts called magnetoencephalograms, or MEGs. The MEGs sense small sources of activity in the brain. As a result, MEGs can define individual sources of electrical activity clearly. This can give doctors information to help diagnose brain disorders. Epilepsy is one illness that is being better diagnosed with the help of MEGs. A person with epilepsy has disrupted electrical rhythms in the brain. MEGs help locate the place in the brain that causes the epilepsy. 1. What is the relationship between magnetism and the human body? 2. Are the magnetic fields produced by the human body large or small? Explain your answer. 3. How are electric currents generated in the human body? 4. What is the relationship between electric currents in the body and magnetism? 5. What do the letters SQUID stand for? What does SQUID do? 6. What are MEGs? What do they show? (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 4

5 21-3 How can you make a magnet? Decide if each of the magnets described is a temporary magnet or a permanent magnet. Write temporary or permanent in the spaces provided. 1. lodestone 2. magnet made from an iron nail 3. nickel magnet 4. magnetite 5. steel magnet 6. soft iron magnet 7. cobalt magnet Skills: writing, analyzing In the space below, write a brief quiz for Lesson Your quiz should include four multiple-choice questions and two short-answer questions. Exchange quizzes with a classmate. After completing the quiz, return it to your classmate. Correct your quiz, and explain why you marked any answers incorrect. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 5

6 21-4 How is Earth like a magnet? Complete each statement. 1. The traps charged particles from the Sun. When the charged particles hit particles in the, an is produced. 2. The of Earth is really like the south pole of a. 3. Canada is the location of Earth s. Earth s is located near the geographic South Pole. 4. The idea that Earth itself is a was first proposed by William Gilbert. 5. The south magnetic pole is really a pole, while the north magnetic pole is really a pole. Skills: locating, observing Look at the drawing of Earth. Label the geographic North Pole and South Pole. Then, label the magnetic south pole and the magnetic north pole. Draw in the magnetosphere. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 6

7 Magnetic Variation Enrichment Activity for Lesson 21-4 Skills: interpreting diagrams, applying concepts The diagram below shows the magnetic and geographic poles of Earth. Use the diagram to answer the questions. 1. What is the relationship between the location of the geographic North Pole and the magnetic south pole? 2. What is the relationship between the location of the geographic South Pole and the magnetic north pole? 3. When a compass points north, is it pointing more toward the geographic or magnetic north pole? 4. The difference between the direction of the geographic North Pole and the magnetic pole near it is called magnetic variation. Would you expect magnetic variation to be greater near the North Pole and South Pole, or near the equator? Why? (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 7

8 21-5 How are electricity and magnetism related? Explain how the terms in each of the following pairs are related. 1. electric current, magnetic field 2. electricity, magnetism 3. Michael Faraday, magnets 4. electromagnetic induction, electric current 5. Oersted, series circuit Skills: experimenting, diagramming Design an experiment to test Oersted s discovery. Include the following: a hypothesis, variables, a procedure, and a type of data to study. In the space provided, draw a diagram showing what your experimental setup would look like. Include labels on your diagram. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 8

9 21-6 What is an electromagnet? Decide which is the stronger electromagnet in each figure, A or B. Write your answers in the spaces provided Skills: analyzing, modeling Choose one of the statements listed below. In the space provided, draw a diagram that illustrates the statement. 1. A coil of wire has a stronger magnetic field than a straight wire. 2. Electromagnets have many important uses. 3. An electromagnet can be made stronger in two different ways. 4. An electromagnet can be turned on and off. 5. The center of an electromagnet is called a core. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 9

10 Electromagnetism Enrichment Activity for Lesson 21-6 Skills: analyzing experiments, interpreting data, drawing conclusions The following experiment was performed by four physical science students. They wanted to find out what factors affect the ability of an electromagnet to attract objects. Read the description of the experiment. Then, answer the questions. Kameko, Justin, Doug, and Elena made an electromagnet by wrapping 50 cm of wire around a core of five iron nails. Then, they connected the free ends of the wire to the positive and negative terminals of a dry cell. They tested the electromagnet to see how many paper clips it would pick up. On their first trial, they found that the magnet would pick up four paper clips. Then, Kameko wrapped another 50 cm of wire around the nails. The students found that now their electromagnet picked up six paper clips. Doug decided to find out what would happen if three of the nails were removed from the magnet. When the students tried to pick up paper clips, they found that the electromagnet would pick up only two paper clips. Elena suggested that they replace the three nails and try increasing the distance between the magnet and the paper clips. The students found that at first the magnet picked up all six paper clips, but that when the distance between the magnet and the paper clips was increased by 5 cm, the magnet picked up only four of the clips. When the distance was increased by another 10 cm, the magnet picked up only two clips. At a distance of 20 cm from the magnet, no paper clips were picked up. 1. What was the purpose of this experiment? State the purpose in the form of a question. 2. What materials did the students use? 3. What were the variables in this experiment? 4. State a possible hypothesis for this experiment. 5. What were the results of the experiment? 6. Based on the results of the experiment, what conclusions can you draw about the factors that affect the strength of an electromagnet? (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 10

11 21-7 What is a transformer? Write true if the statement is true. If the statement is false, change the underlined term to make the statement true. 1. A transformer uses a current in one wire to induce a current in a second wire. 2. The secondary coil is connected to a source of alternating current. 3. A transformer uses alternating current. 4. A step-up transformer has more turns in the primary coil than in the secondary coil. 5. A step-down transformer decreases voltage. 6. Power companies use step-down transformers to send high-voltage electricity over long distances. 7. A step-down transformer is needed before electricity from an electric company can be used in people s homes. 8. A current is induced in the secondary coil whenever a switch in the primary coil is opened or closed. Skills: observing, calculating Use the diagram to answer the questions. Assume that the voltage change is proportional to the number of turns in the different coils of wire. For example, a transformer with three times as many turns on the secondary coil as are on the primary coil will produce three times as much voltage. 1. If the voltage in the primary coil is 120 volts, how many volts are induced in the secondary coil? 2. Is this a step-up or a step-down transformer? (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 11

12 21-8 What is an electric motor? Explain how the terms in each pair are related. 1. electrical energy, mechanical energy 2. permanent magnet, electromagnet 3. attraction, repulsion 4. direct current, motor 5. poles, electromagnet 6. electrical appliances, motors Skills: analyzing, describing On a separate sheet of paper, construct a collage that shows how you use motors in your everyday life. You can cut out pictures of motors from old magazines. Include at least five pictures. Write a brief paragraph describing how your life would be different if electric motors had never been invented. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 12

13 21-9 What is an electric generator? Write true if the statement is true. If the statement is false, change the underlined term to make the statement true. 1. A motor converts mechanical energy into electrical energy. 2. A current can be induced by spinning a loop of wire inside a magnetic field. 3. An electric generator contains a field and an insulated loop of wire. 4. A generator is a large wheel that is turned by water or steam. 5. Power plants use small generators. 6. When a loop of wire cuts magnetic lines of force, a current is induced in the wire. 7. Steam is produced by burning fuels or from running water. 8. The electricity that runs your TV is produced by a motor. Skills: observing, analyzing Use the diagrams to answer the following questions. 1. What is the source of mechanical energy for the generator in Diagram A? 2. What is the source of mechanical energy for the generator in Diagram B? 3. What is the source of mechanical energy for the generator in Diagram C? (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 13

14 Generators Enrichment Activity for Lesson 21-9 Skills: interpreting diagrams, labeling, applying concepts The diagram below shows the operation of a generator. Label the generator, turbine, and power lines. Then, answer the questions. 1. According to the diagram, what is the source of energy for the generator? In what form is this energy? 2. What work does this energy do when it reaches the generator? 3. What causes the electromagnets to move? 4. What is the purpose of the coils of wire surrounding the electromagnets? 5. How does electricity from a generator such as this one reach your home or school? (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 14

15 THE Big IDEA Integrating Technology Chapter 21 How does a maglev train work? Refer to the article, call outs, and Figures on pages 474 and 475 of your text to answer the following questions. 1. What two words is maglev short for? 2. Describe how maglev trains float above their tracks. 3. What advantages do maglev trains have compared to regular trains? 4. What forces are used to pull the cars of a maglev train? 5. What is a superconducting electromagnet? 6. How fast can a maglev train travel? Skill: inferring 1. What would it be like to travel in a maglev train? 2. Why do you think that maglev trains are only experimental right now? 3. What might be some disadvantages of maglev trains? Science Log Writing Activity Complete the Science Log on a separate sheet of paper. To complete the Big Idea Online, go to Follow the online instructions. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 15

16 Chapter 21 Key Term Review In the spaces provided, write the term that best fits each description. Unscramble the letters in brackets [ ] to spell a topic that is discussed in this chapter. Write the topic in the space provided at the bottom of the page. Then, explain the meaning of the topic in one or two sentences. 1. Device that changes mechanical energy into electrical energy [ ] 2. Process by which a material can be made into a magnet [ ] [ ] 3. Temporary magnet made by wrapping a current-carrying wire around an iron core [ ] 4. Force of attraction or repulsion [ ] 5. Region of Earth s magnetic field [ ] [ ] 6. Lines that show the shape of a magnetic field [ ] [ ] 7. Two ends of a magnet [ ] 8. Device that changes electrical energy into mechanical energy [ ] [ ] 9. Process by which an electric current is produced by moving a wire in a magnetic field [ ] [ ] 10. Area around a magnet where magnetic forces can act [ ] 11. Device that uses electromagnetic induction to increase or decrease the voltage of an alternating current [ ] Topic: Explanation: (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 16

17 Chapter 21 Test Interpreting Diagrams Use the diagrams to answer the following questions. A B 1. Which diagram shows an example of a step-up transformer? 2. Which diagram shows an example of repulsion? 3. Which diagram shows an example of a step-down transformer? 4. Which diagram shows an example of attraction? Multiple Choice Write the letter of the term or phrase that best completes each statement. 1. T h e m a g n e t i c p o l e i n t h e E a r t h s S o u t h e r n H e m i s p h e r e i s a c t u a l l y a a. geographic South Pole. b. geographic North Pole. c. north pole. d. south pole. 2. T h e c o i l o f a t r a n s f o r m e r t h a t i s a t t a c h e d t o t h e p o w e r s o u r c e i s t h e a. one with more turns. b. secondary coil. c. one with fewer turns. d. primary coil. 3. E l e c t r i c i t y n e e d e d t o r u n a p p l i a n c e s u s u a l l y c o m e s o r i g i n a l l y f r o m a a. motor. b. magnet. c. generator. d. battery. 4. M a g n e t i s m i s a f o r c e o f a. gravity. b. weight. c. voltage. d. attraction or repulsion. 5. The magnetic lines of force are closest together at a magnet's a. poles. b. north pole. c. south pole. d. middle. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 17

18 Chapter 21 Test (continued) 6. A n e l e c t r i c a p p l i a n c e n e e d s a m o t o r t o c h a n g e e l e c t r i c a l e n e r g y i n t o a. heat energy. b. mechanical energy. c. chemical energy. d. light energy. 7. T h e s c i e n t i s t w h o d i s c o v e r e d t h a t a n e l e c t r i c c u r r e n t c a u s e s a m a g n e t i c f i e l d w a s a. Joseph Henry. b. Michael Faraday. c. Hans Christian Oersted. d. Thomas Edison. 8. An electromagnet is a. a permanent magnet. b. a temporary magnet. c. an alnico magnet. d. a weak magnet. 9. An example of a natural magnet is a. iron. b. aluminum. c. nickel. d. lodestone. 10. Of the following examples, the one that will make an electromagnet with the strongest magnetic field is a a. wire with four coils. b. straight wire. c. wire with three coils. d. wire with two coils. 11. Of the following items, the one that would be attracted to a magnet is a. an iron bar. b. a glass jar. c. a wooden toothpick. d. a plastic cup. 12. When a material, such as an iron nail, is made into a magnet, magnetism has been a. destroyed. b. strengthened. c. weakened. d. induced. 13. Temporary magnets are a. easy to magnetize. b. hard to magnetize. c. always weak magnets. d. always strong magnets. 14. The British scientist who stated that Earth is similar to a bar magnet was a. Nikola Tesla. b. Isaac Newton. c. William Gilbert. d. Michael Faraday. 15. The northern and southern lights can also be called a. auroras. b. magnetospheres. c. magnetic lights. d. solar winds. 16. A transformer that has more turns in the primary coil than in the secondary coil is an example of a a. step-up transformer. b. step-down transformer. c. secondary transformer. d. primary transformer. 17. A device that changes mechanical energy into electrical energy is called a a. motor. b. turbine. c. generator. d. transformer. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 18

19 Chapter 21 Test (continued) Written Response Answer the following questions in complete sentences. 18. EXPLAIN: How are electricity and magnetism related? 19. INFER: How do you think the discovery of the relationship between electricity and magnetism has affected modern society? (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 19

20 Answer Key CHAPTER 21: MAGNETISM 21-1 What is a magnet? 1. not affected 2. attracted 3. attracted 4. not affected 5. not affected 6. attracted 7. attracted 8. attracted 9. attracted 10. not affected What causes magnetism? 1. lines of force 2. a magnetic field 3. at the poles 4. at the poles 5. north pole and south pole 1. attracting 2. repelling 3. repelling Check students drawings for lines of force What causes magnetism? Enrichment Activity: Human Magnetic Fields 1. Organs in the human body have magnetic fields. The most common source is electric currents generated by muscles and nerves. 2. They are extremely small. Very sensitive instruments are needed to detect them. If they were larger, ordinary magnets could detect them. 3. Electric currents are generated by muscles and nerves. The heart and the brain produce the most current. 4. Electric currents generated in the brain and other parts of the body produce magnetic fields. 5. Superconducting Quantum Interference Device; this device detects magnetic fields produced by human organs. 6. magnetoencephalograms; a chart that shows magnetic fields produced by electric currents in the brain 21-3 How can you make a magnet? 1. permanent 2. temporary 3. temporary 4. permanent 5. permanent 6. temporary 7. temporary A possible sample quiz: 1. The process by which a material can be made into a magnet is called: A. magnetic naturalization B. Magnetic induction C. Magnetic temporization D. Magnetic perspiration (Answer: B) 2. Of the following metals, the hardest to magnetize is: A. iron B. nickel C. cobalt D. steel (Answer: D) 3. When materials are magnetized the: A. domains are made to point in the same direction. B. atoms are made to be positive. C. atoms are made to be negative. D. atoms are neutralized. (Answer: A) 4. Materials that are hard to magnetize but keep their magnetism are called: A. permanent magnets. B. temporary magnets. C. rubbed magnets. D. field magnets. (Answer: A) 5. What happens internally to materials that are magnetized? (Answer: Inside the materials, the domains of the materials are made to point in the same direction.) 6. How can a material lose its magnetism? (Answer: A magnet can be dropped and lose its magnetism. It can also lose its magnetism through being heated.) (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 20

21 Answer Key 21-4 How is Earth like a magnet? 1. magnetosphere, atmosphere, aurora 2. north magnetic pole, magnet 3. south magnetic pole, north magnetic pole 4. magnet 5. north, south 21-5 How are electricity and magnetism related? 1. An electric current produces a magnetic field. 2. When a magnetic compass is near an electrical device, the pointer may no longer point north. The relationship is called electromagnetism. 3. Michael Faraday did experiments with magnets to find out if a magnetic field produced an electric current. 4. In electromagnetic induction, an electric current is produced by moving a wire in a magnetic field or by moving a magnet past a stationary wire. 5. Oersted used a series circuit to discover that an electric current produces a magnetic field How is Earth like a magnet? Enrichment Activity: Magnetic Variation 1. They are both high in the Northern Hemisphere, but they are about 1,300 k away from each other. 2. They are both in the Southern Hemisphere, but they are not in exactly the same place. 3. the geographic North Pole 4. near the poles, because the angle between the line connecting the geographic poles and the line connecting the magnetic poles gets larger as one moves closer to the poles Possible answers: Hypothesis: An electric current produces a magnetic field around a wire, affecting a compass needle held nearby. Variables: The amount of electricity running through the wire, and the distance between the compass needle and the wire. Procedure: First, connect the battery to the wire and to the switch. Next, flip the switch, causing an electric current to flow through the wire. Move the compass needle close to the wire, see if the needle responds to the magnetic field. Continuing to hold the compass needle near the wire, turn off the switch. Observe the compass needle. Type of data to study: I will record my observations about what the compass needle does when it is near the wire, and the differences in the compass needle when current is flowing through the wire and when there is no current flowing. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 21

22 Answer Key 21-6 What is an electromagnet? 1. B 2. B Check students diagrams to be sure that they agree with the statement they chose. Possible answers: 1. a coil of wire picking up lots of iron nails beside a straight wire not picking up any 2. a picture of a radio, a telephone, and a computer 3. an electromagnet with very few coils picking up very few nails, next to an electromagnet with lots of coils picking up lots of nails; an electromagnet with a wire labeled weaker current picking up very few nails with an electromagnet labeled strong current picking up lots of nails 4. an electromagnet hooked to a switch labeled on and off with the switch turned to on, and the electromagnet picking up lots of nails; next to it the same electromagnet, but with the switch turned to off above the nails but not picking them up 5. a picture of an electromagnet made of wire wrapped around an iron nail with a line pointing to the nail labeled core 21-6 What is an electromagnet? Enrichment Activity: Electromagnetism 1. What factors affect the strength of an electromagnet? 2. dry cell, 5 iron nails, wire, and paper clips 3. number of loops of wire; size of core (number of nails); and distance between magnet and paper clips 4. The strength of an electromagnet is affected by the number of loops of wire, the size of the magnet, and the distance between the magnet and the object being pulled. 5. The magnet picked up more paper clips when the number of loops of wire was increased. It picked up fewer paper clips when the number of nails in the magnet was decreased. It picked up fewer paper clips as the distance between the magnet and the paper clips increased. 6. The strength of an electromagnet increases with the number of loops of wire, and decreases as the size of the magnet core decreases. The effectiveness of the magnetic field decreases as the distance between the magnet and the object being pulled increases What is a transformer? 1. true 2. primary 3. true 4. fewer 5. true 6. step-up 7. true 8. true volts 2. step-up transformer 21-8 What is an electric motor? Possible answers: 1. An electric motor changes electrical energy into mechanical energy. 2. An electric motor uses both a permanent magnet and an electromagnet. 3. Attraction and repulsion between an electromagnet and a permanent magnet are responsible for the motion of an electric motor. 4. Direct current cannot be used in an electric motor unless a special switch called a commutator is used. 5. You can reverse the poles of an electromagnet by reversing the direction of the current running through it. 6. Many electrical appliances use electric motors. Check students collages. Possible pictures: electric appliances such as dishwashers, blenders, electric ovens, air conditioners, electric tools, and refrigerators Sample paragraph: My life would be different if electric motors had never been invented. The electric motor is one of the main ways in which power plants produce electricity. Without the electric motor, most of the appliances that we use every day, from blenders to blow dryers, would not exist What is an electric generator? 1. generator 2. true 3. magnet 4. turbine 5. large 6. true 7. nuclear energy 8. generator 1. wind 2. waterfall 3. steam (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 22

23 Answer Key 21-9 What is an electric generator? Enrichment Activity: Generators A. power lines B. generator C. turbine 1. moving water; mechanical energy 2. spins the turbine 3. the spinning of the turbine, which in turn spins the magnets 4. As the electromagnets move, the wire cuts magnetic lines of force, producing an electric current. 5. The electric current produced in the wires is conducted to power lines that eventually reach homes, schools, and other buildings. The Big Idea 1. magnetic levitation 2. Maglev trains have magnets on the bottom of the train that are repelled by magnets on the tracks below. Because of this, the train floats above the track. 3. The advantage is that maglev trains have almost no friction as they are gliding above the track. Because of this, they use less fuel than ordinary trains, which means less pollution will be produced. 4. magnetic force 5. an electromagnet that is supercooled so electricity flows through it with almost no resistance 6. about 500 km per hour 1. It would probably be a much smoother, quieter, and faster ride than on an ordinary train. 2. Maglev trains are a new idea, and there are several possible designs for them. Before they become commonplace, engineers need to decide what the best design is. In addition, maglev trains are expensive to build. 3. Possible answers: the large cost associated with building a maglev train; The lack of friction in a train might make it harder to stop the train. The fact that the trains go so fast might make them more dangerous in an accident. CHAPTER 21: MAGNETISM Chapter Test Interpreting Diagrams l. A 2. C 3. B 4. D Multiple Choice 1. c 2. d 3. c 4. d 5. a 6. b 7. c 8. b 9. d 10. a 11. a 12. d 13. a 14. c 15. a 16. b 17. c Written Response 18. Electricity and magnetism are two aspects of the same force. An electric current produces a magnetic field around the wire through which it is running. A moving magnetic field produces a current in a wire through which the field moves. 19. The ability of scientists to use magnetic fields to produce electricity, as it is in generators, has made power plants possible. It has established another source of electricity besides batteries and lightning, allowing engineers to convert mechanical energy into electrical energy. It has also allowed for the invention of the electric motor, which is responsible for our ability to convert the electricity from a power plant back into mechanical energy. CHAPTER 21: MAGNETISM Key Term Review 1. generator 2. magnetic induction 3. electromagnet 4. magnetism 5. magnetosphere 6. magnetic lines of force 7. poles 8. electric motor 9. electromagnetic induction 10. magnetic field 11. transformer Topic: electromagnetism Explanation: Electromagnetism is the relationship between magnetism and electricity. (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Magnetism: CHAPTER 21, page 23