1. NEW CHAPTER the BIG idea Current can produce magnetism, and magnetism can produce current. Magnetism Magnetism is a force that acts at a distance. Current can produce magnetism. Magnetism can produce current. Generators supply electrical energy. CHAPTER CHAPTER OUTLINE 21.1 21.2 21.3 21.4 CHAPTER RESOURCES

2. VOCABULARY KEY CONCEPT CHAPTER HOME Magnetism is a force that acts at a distance. SECTION OUTLINE SECTION OUTLINE magnetism magnet magnetic pole magnetic field magnetic domain The like poles of two magnets repel each other and the opposite poles attract. N S All magnets have a north and south pole. N SN SS N 21.1 CHAPTER RESOURCES CHAPTER RESOURCES

3. VOCABULARY KEY CONCEPT CHAPTER HOME magnet KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Magnetism is a force that acts at a distance. An object that attracts certain other materials, particularly iron and steel. magnetism magnet magnetic pole magnetic field magnetic domain 21.1 CHAPTER RESOURCES CHAPTER RESOURCES

4. VOCABULARY KEY CONCEPT CHAPTER HOME The force exerted by a magnet. Opposite poles of two magnets attract, or pull together, whereas like poles of two magnets repel, or push apart. magnetism KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Magnetism is a force that acts at a distance. magnetism magnet magnetic pole magnetic field magnetic domain 21.1 CHAPTER RESOURCES CHAPTER RESOURCES

5. VOCABULARY KEY CONCEPT CHAPTER HOME One of two ends of a magnet where the magnetic force is the strongest. Every magnet has two poles. magnetic pole KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Magnetism is a force that acts at a distance. magnetism magnet magnetic pole magnetic field magnetic domain 21.1 CHAPTER RESOURCES CHAPTER RESOURCES

6. VOCABULARY KEY CONCEPT CHAPTER HOME An area surrounding a magnet within which the magnet can exert a force. Magnetic fields are concentrated into a pattern of lines that extend from the magnet’s north pole to its south pole. magnetic field KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Magnetism is a force that acts at a distance. magnetism magnet magnetic pole magnetic field magnetic domain 21.1 CHAPTER RESOURCES CHAPTER RESOURCES

7. VOCABULARY KEY CONCEPT CHAPTER HOME A group of atoms whose magnetic fields align, or point in the same direction. Magnetic materials have magnetic domains, whereas nonmagnetic materials do not. magnetic domain KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Magnetism is a force that acts at a distance. magnetism magnet magnetic pole magnetic field magnetic domain 21.1 CHAPTER RESOURCES CHAPTER RESOURCES

8. VOCABULARY KEY CONCEPT CHAPTER HOME electromagnetism Current can produce magnetism. SECTION OUTLINE SECTION OUTLINE electromagnet A magnet that is produced by electric current is called an electromagnet. coil iron core NS 21.2 Explore how current and magnetism are related. SIMULATION CHAPTER RESOURCES CHAPTER RESOURCES

9. VOCABULARY KEY CONCEPT CHAPTER HOME electromagnetism Current can produce magnetism. SECTION OUTLINE SECTION OUTLINE electromagnet A magnet that is produced by electric current is called an electromagnet. Motors use electromagnets to convert electrical energy into the energy of motion. Motor magnet electromagnet 21.2 CHAPTER RESOURCES CHAPTER RESOURCES

10. VOCABULARY KEY CONCEPT CHAPTER HOME electromagnetism Current can produce magnetism. SECTION OUTLINE SECTION OUTLINE electromagnet A magnet that is produced by electric current is called an electromagnet. Motors use electromagnets to convert electrical energy into the energy of motion. 21.2 VISUALIZATION CLASSZONE.COM See a motor in motion. CHAPTER RESOURCES CHAPTER RESOURCES

11. VOCABULARY KEY CONCEPT CHAPTER HOME Magnetism that results from the flow of electric charge. electromagnetism KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Current can produce magnetism. electromagnetism electromagnet 21.2 CHAPTER RESOURCES CHAPTER RESOURCES

12. VOCABULARY KEY CONCEPT CHAPTER HOME A magnet that consists of a piece of iron or steel inside a coil of current-carrying wire. electromagnet KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Current can produce magnetism. electromagnetism electromagnet 21.2 CHAPTER RESOURCES CHAPTER RESOURCES

13. VOCABULARY KEY CONCEPT CHAPTER HOME Magnetism can produce current. SECTION OUTLINE SECTION OUTLINE generator direct current alternating current transformer magnet electromagnet Generator Magnetism can be used to produce electric current. In a generator the energy of motion is converted into electrical energy. 21.3 CHAPTER RESOURCES CHAPTER RESOURCES

14. VOCABULARY KEY CONCEPT CHAPTER HOME A device that converts kinetic energy, or the energy of motion, into electrical energy. Generators produce electric current by rotating a magnet within a coil of wire or rotating a coil of wire within a magnetic field. generator KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Magnetism can produce current. generator direct current alternating current transformer 21.3 CHAPTER RESOURCES CHAPTER RESOURCES

15. VOCABULARY KEY CONCEPT CHAPTER HOME DC Electric current that flows in one direction only. direct current KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Magnetism can produce current. generator direct current alternating current transformer 21.3 CHAPTER RESOURCES CHAPTER RESOURCES

16. VOCABULARY KEY CONCEPT CHAPTER HOME AC Electric current that reverses direction at regular intervals. alternating current KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Magnetism can produce current. generator direct current alternating current transformer 21.3 CHAPTER RESOURCES CHAPTER RESOURCES

17. VOCABULARY KEY CONCEPT CHAPTER HOME A device that uses electromagnetism to increase or decrease voltage. A transformer is often used in the distribution of current from power plants. transformer KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Magnetism can produce current. generator direct current alternating current transformer 21.3 CHAPTER RESOURCES CHAPTER RESOURCES

18. VOCABULARY KEY CONCEPT CHAPTER HOME Generators supply electrical energy. SECTION OUTLINE SECTION OUTLINE watt electric power kilowatt kilowatt-hour Generators at power plants use large magnets to produce electric current, supplying electrical energy to homes and businesses. step-down transformers step-up transformers shaft turbine generator 21.4 CHAPTER RESOURCES CHAPTER RESOURCES

19. VOCABULARY KEY CONCEPT CHAPTER HOME The rate at which electrical energy is generated from, or converted into, another source of energy, such as kinetic energy. electric power KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Generators supply electrical energy. watt electric power kilowatt kilowatt-hour 21.4 CHAPTER RESOURCES CHAPTER RESOURCES

20. VOCABULARY KEY CONCEPT CHAPTER HOME W The unit of measurement for power, which is equal to one joule of work done or energy transferred in one second. For example, a 75 W light bulb converts electrical energy into heat and light at a rate of 75 joules per second. watt KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Generators supply electrical energy. watt electric power kilowatt kilowatt-hour 21.4 CHAPTER RESOURCES CHAPTER RESOURCES

21. VOCABULARY KEY CONCEPT CHAPTER HOME kW A unit of measurement for power equal to 1000 watts. kilowatt KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Generators supply electrical energy. watt electric power kilowatt kilowatt-hour 21.4 CHAPTER RESOURCES CHAPTER RESOURCES

22. VOCABULARY KEY CONCEPT CHAPTER HOME kWh The unit of measurement for electrical energy equal to one kilowatt of power over a one hour period. kilowatt-hour KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Generators supply electrical energy. watt electric power kilowatt kilowatt-hour 21.4 CHAPTER RESOURCES CHAPTER RESOURCES

23. VOCABULARY KEY CONCEPT CHAPTER HOME I. Magnetism is a force that acts at a distance. A. Magnets attract and repel other magnets. C. Earth is a magnet. 1. Earth’s Magnetic Field 2. Magnetism and the Atmosphere KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Magnetism is a force that acts at a distance. 1. Magnetism 2. Magnetic Poles B. Some materials are magnetic. magnetism magnet magnetic pole magnetic field magnetic domain 3. Magnetic Fields 1. Inside Magnetic Materials 2. Temporary and Permanent Magnets 21.1 CHAPTER RESOURCES CHAPTER RESOURCES

24. VOCABULARY KEY CONCEPT CHAPTER HOME KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Current can produce magnetism. II. Current can produce magnetism. A. An electrical current produces a magnetic field. B. Motors use electromagnets. 1. Motors 2. Uses of Motors 1. Electromagnetism 2. Making an Electromagnet 3. Uses of Electromagnets electromagnetism electromagnet 21.2 CHAPTER RESOURCES CHAPTER RESOURCES

25. VOCABULARY KEY CONCEPT CHAPTER HOME III. Magnetism can produce current. A. Magnets are used to generate an electric current. 1. Generating an Electric Current 2. Direct and Alternating Currents B. Magnets are used to control voltage. KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Magnetism can produce current. generator direct current alternating current transformer 21.3 CHAPTER RESOURCES CHAPTER RESOURCES

26. VOCABULARY KEY CONCEPT CHAPTER HOME IV. Generators supply electrical energy. A. Generators provide most of the world’s electrical energy. KEY CONCEPT SUMMARY KEY CONCEPT SUMMARY Generators supply electrical energy. B. Electrical power can be measured. 1. Watts and Kilowatts 2. Calculating Energy Use 1. Generating Electrical Energy watt electric power kilowatt kilowatt-hour 21.4 CHAPTER RESOURCES CHAPTER RESOURCES

27. CHAPTER HOME Image Gallery Click on the icons to see a larger image or animation. Explore how current and magnetism are related. SIMULATIONVISUALIZATION CLASSZONE.COM See a motor in motion.

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34. BACK TO CHAPTER Click on the items below to access resources on Standardized Test Practice Practice state standardized tests Math Tutorial Review math concepts Resource Centers Get more information on select science topics Content Review Review key concepts and vocabulary Audio Readings Hear chapter audio readings CLASSZONE.COM Chapter Resources CHAPTER HOME Animations Link to all the McDougal Littell Science animations Review Game Play a fun interactive review game Image Gallery Click here to review chapter images and animations