In this book John Bird introduces electrical principles and technology through examples rather than theory - enabling students to develop a sound understanding of the principles needed by technicians in fields such as electrical engineering, electronics and telecommunications. No previous background in engineering is assumed, making this an ideal text for vocational courses and introductory courses for undergraduates.

At intervals through the text assessment papers are provided, which are ideal for tests or homeworks. These are the only problems where answers are not provided in the book, but fully worked solutions are available to lecturers only as a free download from http://textbooks.elsevier.com

(d) p.d. between plates to charge 3 The p.d. across a 10 µF capacitor to charge it with 10 mC is (a) 10 V (b) 1 kV (c) 1 V (d) 10 V 4 The charge on a 10 pF capacitor when the voltage applied to it is 10 kV is (a) 100 µC (b) 0.1 C (c) 0.1 µC (d) 0.01 µC 5 Four 2 µF capacitors are connected in parallel. The equivalent capacitance is (a) 8 µF (b) 0.5 µF (c) 2 µF (d) 6 µF 6 Four 2 µF capacitors are connected in series. The equivalent capacitance is (a) 8 µF (b) 0.5 µF (c) 2 µF (d) 6 µF 7

of 0.39 A flows. Find the flux density in the 15 mm length path if the relative permeability of the silicon iron at this value of magnetising force is 3 000. [1.59 T] 4 For the magnetic circuit shown in Fig. 7.7 find the current I in the coil needed to produce a flux of 0.45 mWb in the air-gap. The silicon iron magnetic circuit has a uniform crosssectional area of 3 cm2 and its magnetisation curve is as shown on page 71. [0.83 A] Figure 7.7 5 A ring forming a magnetic circuit is made from two

affect the inductance of an inductor ž draw the circuit diagram symbols for inductors ž calculate the energy stored in an inductor using W D 12 LI2 joules ž calculate inductance L of a coil, given L D N/I ž calculate mutual inductance using E2 D 9.1 Introduction to electromagnetic induction When a conductor is moved across a magnetic field so as to cut through the lines of force (or flux), an electromotive force (e.m.f.) is produced in the conductor. If the conductor forms part of a closed

that work may be done: (a) a supply of energy is required (b) the circuit must have a switch (c) coal must be burnt (d) two wires are necessary 11 The ohm is the unit of: (a) charge (b) resistance (c) power (d) current 12 The unit of current is the: (a) volt (b) coulomb (c) joule (d) ampere TLFeBOOK 2 An introduction to electric circuits At the end of this chapter you should be able to: ž appreciate that engineering systems may be represented by block diagrams ž recognize common electrical

network shown in Fig. 13.9 determine the currents in each of the resistors. 176I2 D 864 16 ð 1 gives: 3 4 592I2 D 592 3 gives: I2 D 1 A Substituting for I2 in (1) gives: 13I1 11 D 54 I1 D 65 D 5A 13 Hence, the current flowing in the 2 resistor D I1 D 5 A Figure 13.9 the current flowing in the 14 Let the current in the 2 resistor be I1 , then by Kirchhoff’s current law, the current in the 14 resistor is I I1 . Let the current in the 32 resistor be I2 as shown in Fig. 13.10. Then the