Ch. 3 Magnetism and Electromagnetism Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Magnetic field lines around a bar magnet a. are only perpendicular to the magnet. b. spread out from one pole and curve around to the other. c. cross back and forth over one another. d. are perfectly straight. 2. Every magnet, regardless of its shape, has two a. magnetic poles. b. magnetic charges. c. magnetic fields. d. magnetic needles. 3. Magnetic poles that are unlike a. attract each other. b. repel each other. c. do not interact. d. point in the same direction. 4. What is one difference between a galvanometer and an electric motor? a. An electric motor causes something to move. b. A galvanometer uses an electric current. c. In an electric motor, the armature spins continuously. d. An electric motor uses electrical energy. 5. To reverse the direction of current in a motor, current is conducted a. through the armature. b. in the direction of rotation. c. through the brushes to the commutator. d. through the commutator to the armature. 6. The type of current produced by a battery is a. direct current. b. alternating current. c. magnetic current. d. induced current. 7. You can increase the strength of an electromagnet s field by a. decreasing the current in the solenoid. b. decreasing the number of loops in the solenoid. c. using a stronger ferromagnetic material for the core. d. winding the coils more loosely. 8. As Earth s magnetic poles move, the magnetic declination in a given location will a. stay the same. b. switch to point south. c. change. d. return to zero.
9. An electric current produces a(n) a. magnetic field. b. magnet. c. solenoid. d. insulator. 10. Electric current from a generating plant is a. direct current transmitted at high voltages, but usually used at low voltages. b. alternating current transmitted at high voltages, but usually used at low voltages. c. alternating current transmitted at low voltages, but usually used at high voltages. d. direct current transmitted at low voltages, but usually used at high voltages. 11. Magnetic poles that are alike a. attract each other. b. repel each other. c. do not interact. d. have the same shape. 12. The two ends of a solenoid act like a. electrons. b. a compass needle. c. a circuit. d. poles of a magnet. 13. A solenoid with a ferromagnetic core is called a(n) a. electromagnet. b. magnetic pole. c. lodestone. d. temporary magnet. 14. A device used to measure small currents is a(n) a. electric motor. b. commutator. c. armature. d. galvanometer. 15. What device transforms electrical energy into mechanical energy? a. an electromagnet b. an electric motor c. a generator d. a solenoid 16. A generator transforms a. potential energy into kinetic energy. b. mechanical energy into electrical energy. c. magnetic energy into electrical energy. d. friction into electrical energy. 17. A device that increases or decreases voltage is called a(n) a. alternator. b. transformer. c. generator.
d. turbine. Completion Complete each statement. 18. A maglev train floats above its rails due to. 19. A galvanometer is a device that measures small. 20. When a wire moves up or down repeatedly in a(n), an alternating current is induced in the wire. 21. A step-up transformer is a transformer that increases. 22. A(n) is a strong magnet that can be turned on and off. 23. A(n) is any material that attracts iron and materials that contain iron. 24. When placed near each other, unlike magnetic poles each other. 25. A(n) is the region of magnetic force around a magnet. 26. A(n) is produced around a wire through which a current flows. 27. A solenoid with a(n) core is called an electromagnet. 28. The distance that the pointer of a galvanometer moves depends on the amount of in the loops of the armature. 29. A current consisting of charges that flow in one direction only is called a(n) current. 30. To generate electricity at an electric company, a turbine is attached to the of a generator.
Ch. 3 Magnetism and Electromagnetism Answer Section MULTIPLE CHOICE 1. ANS: B DIF: L2 OBJ: Describe a magnetic field. TOP: n_ch01_006 BLM: comprehension 2. ANS: A DIF: L1 OBJ: Explain how magnetic poles interact. TOP: n_ch01_019 3. ANS: A DIF: L1 OBJ: Explain how magnetic poles interact. TOP: n_ch01_016 4. ANS: C DIF: L2 OBJ: Describe how galvanometers work. TOP: n_ch03_003 BLM: application 5. ANS: C DIF: L2 OBJ: Describe how electric motors work TOP: n_ch03_004 BLM: comprehension 6. ANS: A DIF: L2 OBJ: Explain how an electric current can be produced in a conductor. TOP: n_ch03_006 BLM: comprehension 7. ANS: C DIF: L2 TOP: n_ch03_016 BLM: comprehension 8. ANS: C DIF: L2 OBJ: Describe Earth s magnetic field. TOP: n_ch01_025 BLM: comprehension 9. ANS: A DIF: L1 OBJ: Explain how electric current is related to magnetism. TOP: n_ch03_020 10. ANS: B DIF: L2 OBJ: Describe the function of a transformer. TOP: n_ch03_011 BLM: application 11. ANS: B DIF: L1 OBJ: Explain how magnetic poles interact. TOP: n_ch01_002 12. ANS: D DIF: L2 OBJ: Identify some characteristics of a magnetic field produced by a current. TOP: n_ch03_023 BLM: comprehension 13. ANS: A DIF: L1 TOP: n_ch03_015 14. ANS: D DIF: L1 OBJ: Describe how galvanometers work. TOP: n_ch03_012 15. ANS: B DIF: L1 OBJ: Describe how electric motors work TOP: n_ch03_026 16. ANS: B DIF: L1 OBJ: Describe how a generator works. TOP: n_ch03_008 17. ANS: B DIF: L1
OBJ: Describe the function of a transformer. TOP: n_ch03_009 COMPLETION 18. ANS: magnetism DIF: L2 OBJ: Identify and describe the properties of magnets. TOP: n_ch01_042 BLM: comprehension 19. ANS: currents DIF: L1 OBJ: Describe how galvanometers work. TOP: n_ch03_042 20. ANS: magnetic field DIF: L2 OBJ: Explain how an electric current can be produced in a conductor. TOP: n_ch03_045 BLM: comprehension 21. ANS: voltage DIF: L1 OBJ: Describe the function of a transformer. TOP: n_ch03_050 22. ANS: electromagnet DIF: L1 TOP: n_ch03_059 23. ANS: magnet DIF: L1 OBJ: Identify and describe the properties of magnets. TOP: n_ch01_057 24. ANS: attract DIF: L1 OBJ: Explain how magnetic poles interact. TOP: n_ch01_041 25. ANS: magnetic field DIF: L1 OBJ: Describe a magnetic field. TOP: n_ch01_046 26. ANS: magnetic field DIF: L2 OBJ: Explain how electric current is related to magnetism. TOP: n_ch03_058 BLM: comprehension 27. ANS: ferromagnetic DIF: L2 TOP: n_ch03_057 BLM: comprehension 28. ANS: current
DIF: L2 OBJ: Describe how galvanometers work. TOP: n_ch03_043 BLM: comprehension 29. ANS: direct DIF: L1 OBJ: Explain how an electric current can be produced in a conductor. TOP: n_ch03_052 30. ANS: armature DIF: L2 OBJ: Describe how a generator works. TOP: n_ch03_049 BLM: comprehension