Robertson C.R. Fundamental electrical and electronic principles
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Fundamental Electrical
and Electronic
Principles
Third Edition
Christopher R Robertson
AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD
PARIS • SAN DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO
Newnes is an imprint of Elsevier
Newnes is an imprint of Elsevier
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First published 1993 as Electrical and Electronic Principles 1 by Edward Arnold
Second edition 2001
Third edition 2008
Copyright © C. R. Robertson 1993, 2001
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Preface ........................................................................................................................................................ix
Introduction ............................................................................................................................................xi
1
Fundamentals ...........................................................................1
1.1 Units .................................................................................................................................................1
1.2 Standard Form Notation ......................................................................................................2
1.3 ‘ Scienti c ’ Notation ..................................................................................................................2
1.4 Conversion of Areas and Volumes .................................................................................4
1.5 Graphs .............................................................................................................................................5
1.6 Basic Electrical Concepts .....................................................................................................7
1.7 Communication .....................................................................................................................26
Summary of Equations ......................................................................................................29
Assignment Questions ......................................................................................................30
2
D.C. Circuits ............................................................................................. 31
2.1 Resistors in Series ..................................................................................................................31
2.2 Resistors in Parallel ...............................................................................................................35
2.3 Potential Divider ....................................................................................................................40
2.4 Current Divider .......................................................................................................................41
2.5 Series/Parallel Combinations .........................................................................................43
2.6 Kirchho ’ s Current Law .....................................................................................................48
2.7 Kirchho ’ s Voltage Law .....................................................................................................49
2.8 The Wheatstone Bridge Network ................................................................................55
2.9 The Wheatstone Bridge Instrument ..........................................................................63
2.10 The Slidewire Potentiometer .........................................................................................65
Summary of Equations ......................................................................................................68
Assignment Questions ......................................................................................................69
Suggested Practical Assignments ..............................................................................72
3
Electric Fields and Capacitors .................................................... 75
3.1 Coulomb ’ s Law .......................................................................................................................75
3.2 Electric Fields ...........................................................................................................................76
3.3 Electric Field Strength (E) .................................................................................................78
3.4 Electric Flux () and Flux Density (D) .......................................................................79
3.5 The Charging Process and Potential Gradient ....................................................80
3.6 Capacitance (C) ......................................................................................................................83
3.7 Capacitors ..................................................................................................................................84
3.8 Permittivity of Free Space (ε
0
) .......................................................................................84
3.9 Relative Permittivity (ε
r
) .....................................................................................................84
3.10 Absolute Permittivity (ε) ...................................................................................................85
Contents
v
vi
Contents
3.11 Calculating Capacitor Values ..........................................................................................85
3.12 Capacitors in Parallel ...........................................................................................................87
3.13 Capacitors in Series ..............................................................................................................89
3.14 Series/Parallel Combinations .........................................................................................92
3.15 Multiplate Capacitors .........................................................................................................95
3.16 Energy Stored ..........................................................................................................................97
3.17 Dielectric Strength and Working Voltage ...........................................................101
3.18 Capacitor Types ...................................................................................................................102
Summary of Equations ...................................................................................................105
Assignment Questions ...................................................................................................107
Suggested Practical Assignment .............................................................................110
4
Magnetic Fields and Circuits ..................................................... 111
4.1 Magnetic Materials ............................................................................................................111
4.2 Magnetic Fields ...................................................................................................................111
4.3 The Magnetic Circuit ........................................................................................................114
4.4 Magnetic Flux and Flux Density ................................................................................115
4.5 Magnetomotive Force (mmf) ....................................................................................116
4.6 Magnetic Field Strength ................................................................................................117
4.7 Permeability of Free Space (
0
) .................................................................................118
4.8 Relative Permeability (
r
) ...............................................................................................119
4.9 Absolute Permeability () .............................................................................................119
4.10 Magnetisation (B/H) Curve ...........................................................................................122
4.11 Composite Series Magnetic Circuits ......................................................................126
4.12 Reluctance (S) .......................................................................................................................128
4.13 Comparison of Electrical, Magnetic and Electrostatic Quantities ........131
4.14 Magnetic Hysteresis .........................................................................................................132
4.15 Parallel Magnetic Circuits ..............................................................................................134
Summary of Equations ...................................................................................................135
Assignment Questions ...................................................................................................136
Suggested Practical Assignments ...........................................................................138
5
Electromagnetism .......................................................................... 141
5.1 Faraday ’ s Law of Electromagnetic Induction ....................................................141
5.2 Lenz ’ s Law ...............................................................................................................................144
5.3 Fleming ’ s Righthand Rule .............................................................................................144
5.4 EMF Induced in a Single Straight Conductor ...................................................147
5.5 Force on a Current-Carrying Conductor ..............................................................151
5.6 The Motor Principle ..........................................................................................................153
5.7 Force between Parallel Conductors .......................................................................156
5.8 The Moving Coil Meter ...................................................................................................158
5.9 Shunts and Multipliers ....................................................................................................162
5.10 Shunts .......................................................................................................................................162
5.11 Multipliers ...............................................................................................................................163
Contents
vii
5.12 Figure of Merit and Loading E ect .........................................................................166
5.13 The Ohmmeter ....................................................................................................................170
5.14 Wattmeter ...............................................................................................................................171
5.15 Eddy Currents .......................................................................................................................172
5.16 Self and Mutual Inductance ........................................................................................174
5.17 Self-Inductance ...................................................................................................................175
5.18 Self-Inductance and Flux Linkages .........................................................................176
5.19 Factors A ecting Inductance .....................................................................................179
5.20 Mutual Inductance ............................................................................................................180
5.21 Relationship between Self- and Mutual-Inductance ...................................182
5.22 Energy Stored .......................................................................................................................184
5.23 The Transformer Principle .............................................................................................186
5.24 Transformer Voltage and Current Ratios ..............................................................188
Summary of Equations ...................................................................................................191
Assignment Questions ...................................................................................................192
Suggested Practical Assignments ...........................................................................195
6
Alternating Quantities ................................................................ 197
6.1 Production of an Alternating Waveform .............................................................197
6.2 Angular Velocity and Frequency ..............................................................................200
6.3 Standard Expression for an Alternating Quantity ..........................................200
6.4 Average Value .......................................................................................................................203
6.5 r.m.s. Value ..............................................................................................................................205
6.6 Peak Factor .............................................................................................................................206
6.7 Form Factor ............................................................................................................................207
6.8 Recti ers ..................................................................................................................................208
6.9 Half-wave Recti er ............................................................................................................209
6.10 Full-wave Bridge Recti er .............................................................................................210
6.11 Recti er Moving Coil Meter .........................................................................................212
6.12 Phase and Phase Angle ..................................................................................................213
6.13 Phasor Representation ....................................................................................................216
6.14 Addition of Alternating Quantities ..........................................................................219
6.15 The Cathode Ray Oscilloscope ..................................................................................224
6.16 Operation of the Oscilloscope ...................................................................................226
6.17 Dual Beam Oscilloscopes ..............................................................................................228
Summary of Equations ...................................................................................................229
Assignment Questions ...................................................................................................230
Suggested Practical Assignments ...........................................................................232
7
D.C. Machines .................................................................................... 233
7.1 Motor/Generator Duality ..............................................................................................233
7.2 The Generation of d.c. Voltage ...................................................................................235
7.3 Construction of d.c. Machines ................................................................................... 238
7.4 Classi cation of Generators .........................................................................................238
viii
Contents
7.5 Separately Excited Generator .....................................................................................239
7.6 Shunt Generator .................................................................................................................240
7.7 Series Generator .................................................................................................................242
7.8 D. C. Motors ...........................................................................................................................244
7.9 Shunt Motor ..........................................................................................................................244
7.10 Series Motor ..........................................................................................................................245
Summary of Equations ...................................................................................................247
Assignment Questions ...................................................................................................248
8
D.C. Transients ................................................................................... 249
8.1 Capacitor-Resistor Series Circuit (Charging) ......................................................249
8.2 Capacitor-Resistor Series Circuit (Discharging) ...............................................253
8.3 Inductor-Resistor Series Circuit (Connection to Supply) ...........................256
8.4 Inductor-Resistor Series Circuit (Disconnection) ............................................259
Summary of Equations ...................................................................................................260
Assignment Questions ...................................................................................................261
Suggested Practical Assignments ...........................................................................262
9
Semiconductor Theory and Devices ................................... 263
9.1 Atomic Structure ................................................................................................................263
9.2 Intrinsic (Pure) Semiconductors ................................................................................264
9.3 Electron-Hole Pair Generation and Recombination .....................................266
9.4 Conduction in Intrinsic Semiconductors ............................................................267
9.5 Extrinsic (Impure) Semiconductors ........................................................................268
9.6 n-type Semiconductor ...................................................................................................268
9.7 p-type Semiconductor ...................................................................................................270
9.8 The p-n Junction ................................................................................................................271
9.9 The p-n Junction Diode .................................................................................................272
9.10 Forward-biased Diode ....................................................................................................273
9.11 Reverse-biased Diode .....................................................................................................273
9.12 Diode Characteristics .......................................................................................................274
9.13 The Zener Diode .................................................................................................................276
Assignment Questions ...................................................................................................281
Suggested Practical Assignments ...........................................................................282
Appendix A: SI Units and Quantities ..................................................................................283
Answers to Assignment Questions .....................................................................................285
Index .......................................................................................................................................................289
This Textbook supersedes the second edition of Fundamental
Electrical and Electronic Principles. In response to comments
from colleges requesting that the contents more closely match the
objectives of the BTEC unit Electrical and Electronic Principles,
some chapters have been removed and some exchanged with the
companion book Further Electrical and Electronic Principles, ISBN
9780750687478. Also, in order to encourage students to use other
reference sources, those chapters that have been totally removed
may be accessed on the website address http://books.elsevier.
com/companions/9780750687379. The previous edition included
Supplementary Worked Examples at the end of each chapter. The
majority of these have now been included within each chapter as
Worked Examples, and those that have been removed may be accessed
on the above website.
This book continues with the philosophy of the previous editions
in that it may be used as a complete set of course notes for students
undertaking the study of Electrical and Electronic Principles in the
fi rst year of a BTEC National Diploma/Certifi cate course. It also
provides coverage for some other courses, including foundation/
bridging courses which require the study of Electrical and Electronic
Engineering.
Fundamental Electrical and Electronic Principles contains 349
illustrations, 112 worked examples, 26 suggested practical assignments
and 234 assignment questions. The answers to the latter are to be found
towards the end of the book.
The order of the chapters does not necessarily follow the order
set out in any syllabus, but rather follows a logical step-by-step
sequence through the subject matter. Some topic areas may extend
beyond current syllabus requirements, but do so both for the sake of
completeness and to encourage those students wishing to extend their
knowledge.
Coverage of the second year BTEC National Diploma/Certifi cate
unit, Further Electrical Principles, is found in the third edition of the
companion book Further Electrical and Electronic Principles.
C. Robertson
Tonbridge
March 2008
Preface
ix
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The chapters follow a sequence that I consider to be a logical
progression through the subject matter, and in the main, follow
the order of objectives stated in the BTEC unit of Electrical and
Electronic Principles. The major exception to this is that the topics of
instrumentation and measurements do not appear in a specifi c chapter
of that title. Instead, the various instruments and measurement methods
are integrated within those chapters where the relevant theory is
covered.
Occasionally a word or phrase will appear in
bold blue type, and close
by will be a box with a blue background. These emphasised words or
phrases may be ones that are not familiar to students, and within the
box will be an explanation of the words used in the text.
Throughout the book, Worked Examples appear as Q questions
in bold type, followed by A answers. In all chapters, Assignment
Questions are provided for students to solve.
The fi rst chapter deals with the basic concepts of electricity; the use of
standard form and its adaptation to scientifi c notation; SI and derived
units; and the plotting of graphs. This chapter is intended to provide
a means of ensuring that all students on a given course start with the
same background knowledge. Also included in this chapter are notes
regarding communication. In particular, emphasis is placed on logical
and thorough presentation of information, etc. in the solution of
Assignment Questions and Practical Assignment reports.
Introduction
xi
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