Copyright Goodheart-Willcox Co., Inc. Magnetism CHAPTER 12 97 Objectives After studying this chapter, you will be able to: „ Explain how natural magnets were first discovered and used. „ State the basic laws of magnetic materials. „ Describe how electric current can produce magnetic fields. „ Discuss the common applications of the electromagnet. „ Describe the operation of the relay and why it is so important in electrical applications. Technical Terms ampere-turn electromagnet induction left-hand rule for a coil lodestone magnet magnetic field magnetic flux magnetic material magnetic shielding north pole permeability relay reluctance residual magnetism solenoid south pole Drill and Practice E-flash Cards Matching Activity Vocabulary Game