This is module 3 of 14 modules.

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Introduction

Inductors are less common than resistors or capacitors in most circuits. However, in A.C. circuits they are extremely useful. The action of inductors changes at different frequencies, so they can be used in many frequency sensitive applications such as radio (including mobile phones), and audio, where they can help in determining which range of frequencies the device receives. Inductors are also sensitive to the presence of magnetic fields and to magnetic materials such as iron and steel. They can even be used to sense when a car is approaching traffic lights. This module introduces different types of inductors and describes their basic construction. Later modules look at how inductors are used in AC circuits where, together with capacitors, they perform many important functions.