Inductor

The Inductor, also called a choke, is another passive type electrical component designed to take advantage of the principle that a current carrying coil has a magnetic flux developed across it, whose magnitude is directly proportional to the amount of current, (direction given by Fleming’s Left Hand rule). It induces a voltage into the coil to oppose any change in the electrical current flowing through it. So, in an inductor, the magnetic field reacts to oppose any change in the current.

Fig7

All the inductors are categorised into fixed and variable used for different applications. There are filter chokes that are used in smoothing the pulsating current. Also, depending on the frequency range there are audio- frequency chokes (AFC) or radio- frequency chokes (RFC). The fixed inductors can be further classified into three main types namely air inductors, iron-core inductors and ferrite core inductors. Variable inductors are similar to fixed ferrite core inductors, but the core is adjustable which can be slid in or out of the coil.

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Inductance: The reaction of magnetic field trying to make the current steady is known as inductance and the force which it develops is called induced emf. Thus, inductance is the measure of energy stored in the coil in the form of magnetic field and has the ability to produce induced voltage whenever current varies through it. The unit of Inductance is Henry (H).

Inductance Value Inductors come in many different sizes. So, the larger ones have their technical specifications written on the package while the moderate to smaller ones use numerical colour codes. Besides their inductance value, tolerance is also an important specification which is marked on most of the inductor packages. Most of the inductors have their inductance in micro- or milli-Henry range.