IA R AL AU ST EN SA G M AG PL E E L PA EA G RN ES I N G C O F TY PE R O PR ISBN: 978-0170192743 For learning solutions, visit cengage.com.au 9 780170 192743 PHILLIPS 2ed SB 9780170196307 CVR FINAL ART.indd 1 16/12/11 9:16 AM Brief contents Chapter 1 The electric circuit Chapter 2 Voltage sources and effects of an electric current Chapter 3 Ohm’s law AU 1 ST R Prefacexvi Resources guide xvii Acknowledgementsxx About the author xxi AL I A Brief contents v 24 43 Chapter 5 Resistance and resistors Chapter 6 The series circuit Chapter 7 The parallel circuit 63 SA G M AG PL E E L PA EA G RN ES I N G Chapter 4 Electrical power 88 108 125 Chapter 8 The series–parallel circuit 143 Chapter 9 Basic meters 157 Chapter 10 Capacitance 188 Chapter 11 Magnetism and electromagnets 220 Chapter 12 Electromagnetic induction 251 Chapter 13 DC generators 269 Chapter 14 DC motors 299 Chapter 15 AC fundamentals 331 358 Chapter 17 Series combinations of R, L and C 377 Chapter 18 Parallel AC circuits 400 EN Chapter 16 Pure R, L or C in an AC circuit Chapter 19 Single-phase power C Chapter 20 Three-phase power 418 435 Chapter 21 Transformers474 519 Chapter 23 Single-phase motors 555 Chapter 24 Synchronous machines 569 Chapter 25 Test equipment and batteries 594 TY O F Chapter 22 Three-phase motors PR O PE R Appendix637 Solutions640 Index656 00_Phillips 2ed SB 9780170192743 TXT.indd 5 21/02/13 4:11 PM 27 CHAPTER 2 Voltage sources and effects of an electric current FIGURE 2.4 Piezo-electric effect, where pressure is applied to opposite faces of a quartz crystal to produce a voltage. Pressure can be by compressing, flexing or distorting the piezo element. F C EN SA G M AG PL E E L PA EA G RN ES I N G AU ST R AL The piezo-electric effect was discovered in 1880 by the Curie brothers. (Piezo is Greek for pressure.) They found that when mechanical stress was applied to crystals such as topaz, quartz, Rochelle salt and cane sugar, electrical charges appeared, and that this voltage was proportional to the applied stress. Materials that have this characteristic are called piezo-electric materials. The piezo-electric effect occurs when the charge balance within the crystal lattice of a piezo material is disturbed. When there is no applied stress on the material, the positive and negative charges are evenly distributed so there is no potential difference. When the lattice is changed slightly, the charge imbalance creates a potential difference, often as high as several thousand volts. However, the current is extremely small and only causes a small electric shock. Piezo elements are used in electronic cigarette lighters, gas lighters, guitar pick-ups, some kinds of microphones and various types of sensors, such as accelerometers. When used in electronic gas lighters, a trigger-operated mechanical mechanism is arranged to apply a short, sharp force to the piezeo element, which produces a voltage that is high enough to cause a spark, as in Figure 2.4. In a microphone, the variations in air pressure due to sound waves cause the piezo-electric crystal element in the microphone to produce a very small voltage that changes with the sound waves. IA Piezo-electric crystal O Magnetism PR O PE R TY Magnetism plays a big role in the electrotechnology industry, and the topics of magnetism and electromagnetism are covered in Chapters 11 and 12. In principle, if a conductor is moved through a magnetic field, a voltage is induced in the conductor. This effect was discovered by Michael Faraday in 1831, a discovery that led to the electrical power generation industry of today. Figure 2.5 shows a single conductor being moved through a magnetic field, although the voltage it produces will be very small (a few millionths of a volt). Faraday found that the faster the conductor moves through a magnetic field, the higher the voltage. It doesn’t matter whether the magnetic field or the conductor moves – a voltage is produced if either moves relative to the other. He also found 02_Electrical Principles 2ed SB 9780170192743 TXT.indd 27 FIGURE 2.5 Producing a voltage by using mechanical energy to move a conductor in a magnetic field 21/02/13 1:23 PM A AL I ST R AU G SA G M AG PL E E L PA EA G RN ES I N EN C F O TY R PE PR O 12_Electrical Principles 2ed SB 9780170192743 TXT hires.indd 259 12/9/11 10:24 AM IA AL ST R AU G EN SA G M AG PL E E L PA EA G RN ES I N C F O TY PE R O PR 24_Electrical Principles 2ed SB 9780170192743 TXT hires.indd 572 12/9/11 10:58 AM