FIGURE 4-1 Magnetic field patterns when magnets are placed end to end. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-2 Magnetic flux lines distorted while passing through a piece of iron. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-3 Horseshoe magnet. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-4 Magnetic fields: (a) left-hand rule of magnetic flux; (b) cross section of a conductor with current flow toward the observer; (c) cross section of a conductor with current flow away from the observer; (d) compass aligns tangent to the circular magnetic lines of force. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-5 Magnetic field around a loop of wire. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-6 Magnetic field around a coil: (a) coil of wire showing current flow; (b) lines of force around two loops that are parallel; (c) cross section of a coil showing lines of force. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-7 Electromagnets: (a) pictorial; (b) an electromagnet in operation.[(b) Courtesy of O.S. Walker Co.] Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-7 continued Electromagnets: (a) pictorial; (b) an electromagnet in operation.[(b) Courtesy of O.S. Walker Co.] Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-8 Left-hand rule for finding the polarities of an electromagnet. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-9 Effect of ampere-turns on magnetic field strength: (a) five turns and two amperes = 10 ampere-turns; (b) eight turns and two amperes = 16 ampere-turns. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. (a)

FIGURE 4-9 continued Effect of ampere-turns on magnetic field strength: (a) five turns and two amperes = 10 ampere-turns; (b) eight turns and two amperes = 16 ampere-turns. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. (b)

FIGURE 4-10 Effect of an iron core on magnetic strength: (a) coil without a core; (b) coil with a core. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. (a)

FIGURE 4-10 continued Effect of an iron core on magnetic strength: (a) coil without a core; (b) coil with a core. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. (b)

FIGURE 4-11 Relationship of magnetic and electrical terms. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-12 Domain theory of magnetism: (a) unmagnetized; (b) slightly magnetized; (c) fully magnetized-saturation. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-12 continued Domain theory of magnetism: (a) unmagnetized; (b) slightly magnetized; (c) fully magnetized-saturation. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-12 continued Domain theory of magnetism: (a) unmagnetized; (b) slightly magnetized; (c) fully magnetized-saturation. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-13 Faraday’s law-electrical current is produced when there is relative motion between a conductor and a magnetic field. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-14 Construction and symbols of a relay: (a) pictorial; (b) symbols; (c) illustration. [(a) Courtesy of Airpax Corp., Cambridge Division.] Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-14 Construction and symbols of a relay: (a) pictorial; (b) symbols; (c) illustration. [(a) Courtesy of Airpax Corp., Cambridge Division.] Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. (b)

FIGURE 4-14 continued Construction and symbols of a relay: (a) pictorial; (b) symbols; (c) illustration. [(a) Courtesy of Airpax Corp., Cambridge Division.] Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. (c)

FIGURE 4-15 Schematic diagram of a relay circuit. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-16 Solenoid devices. [(b) Courtesy of Magnet-Schultz of America, Inc.] Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-16 continued Solenoid devices. [(b) Courtesy of Magnet-Schultz of America, Inc.] Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-17 Magnetic motor contactor. (Courtesy of Furnas Electric Co.) Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-18 Magnetic circuit breaker. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-19 Electric bell. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-20 Reed devices: (a) reed relay; (b) reed switch; (c) reed switch as part of a home security system; (d) open and closed reed switch contacts. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-20 Reed devices: (c) reed switch as part of a home security system. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. (c)

FIGURE 4-20 continued Reed devices: (c) reed switch as part of a home security system. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-21 Moving coil meter movement. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-22 Electromagnetic tape recording principle. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-23 Electromagnetic speaker. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-24 Magnetization or B-H curve. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.

FIGURE 4-25 Illustration showing the Hall effect. Dale R. Patrick Electricity and Electronics: A Survey, 5e Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved.