Page 10 - Teach Yourself Electricity and Electronics

x Contents

Magnetic field strength 139
Permeability 142
Retentivity 142
Permanent magnets 143
The solenoid 144
The dc motor 145
Magnetic data storage 146
Quiz 149
Test: Part 1 153

Part 2 Alternating current

9 Alternating current basics 165
Definition of alternating current 165
Period and frequency 165
The sine wave 167
The square wave 167
Sawtooth waves 167
Complex and irregular waveforms 169
Frequency spectrum 170
Little bits of a cycle 172
Phase difference 173
Amplitude of alternating current 173
Superimposed direct current 175
The ac generator 176
Why ac? 178
Quiz 178

10 Inductance 183
The property of inductance 183
Practical inductors 184
The unit of inductance 185
Inductors in series 185
Inductors in parallel 186
Interaction among inductors 187
Effects of mutual inductance 188
Air-core coils 189
Powdered-iron and ferrite cores 190
Permeability tuning 190
Toroids 190
Pot cores 192
Filter chokes 192
Inductors at audio frequency 193
Inductors at radio frequency 193
Transmission-line inductors 193