Inductor

Inductor is a device that stores energy in the form of magnetic field. A straight wire bent into the form of a coil possesses inductance which is known as self inductance of the coil.

An Inductor offers resistance to the flow of AC through it. A pure inductance doesn't offer any resistance to the flow of DC through it. There are three main types of inductors and they are as follows

• An air core inductor
• Iron core inductor
• A special type of Inductor called toroid

An Air Core Inductor:

In most electronic applications of inductance where space is limited, wire is wound into either single-layer or multi-layer coils with air. Such an Inductor is known as air core inductor.

Iron Core Inductor:

 When an Inductor has core made of thin iron sheet or ferrite cores, it is known an iron core inductor. Ferrite materials like zinc or manganese-iron oxides have magnetic permeability but are insulators. Therefore a coil with a ferrite core makes an Inductor of inductance many times more than that of an air core inductor. In many applications, coils are wound around a ferrite cylinder that can be screwed into or out of the core space of the coil. This results in controlled variations of inductance. The Inductor has maxim inductance when the iron core (slug) is screwed into the coil and the inductance is minimum, when the slug is backed out.

A special type of Inductor or toroid:

A special type of Inductor called toroid which consists of a doughnut-shaper ferrite core, either single-layer-wound as shown in the figure below or multi-layer-wound. Such an Inductor has high values of inductance with less wire and therefore little resistance in the coil. Moreover all the lines of force remain in the core. As a result of which, no shielding is required to prevent its field from surrounding circuits or electrical appliances. Even two toroids very close to each other will have no interaction between them.

Questionnaire:

• What is Inductor?
• What are the types of Inductors?