Inductor

An inductor is a passive device employed in the majority of power electronic circuits to store energy in magnetic form when it is energised by an electric current. One of the most important characteristics of an inductor is that it resists or opposes any change in the current flowing through it. Whenever the inductor's current changes, it either gains energy or releases energy in an attempt to maintain the current flowing through it. The inductor can also be referred to as a choke.

Structure of an Inductor

It is usually constructed from a coil of wire, typically wound around a magnetic material core such as iron or ferrite. The shape of the coil enhances the magnetic field and thus the inductance. The core material strengthens the magnetic field and facilitates greater energy storage.

Types of Inductors:

Air-core Inductors- These inductors have no magnetic core, but the number of turns the inductor must have is greater for this type when compared to the inductors with a core. They are used in high-frequency applications.
Ferrite-core or Iron-core Inductors -Ferrite materials are used as the core in this inductor. They are used when a higher value of inductance is needed.

Inductors in Parallel Form

If the corresponding terminals of two inductors are connected together, then the inductors are referred to as being parallel. We are aware of the fact that whenever resistors are joined in parallel, their effective resistance reduces. Likewise, if the inductors are joined in parallel form, their effective inductance reduces. Parallel inductors are like the capacitors joined in series. The current passing through each inductor will differ. But the voltage across every inductor will remain the same.

Formula -

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Inductors in Series

When the inductors are connected end-to-end, then the inductors are referred to as being in series connection. When inductors are in series, the overall inductance is the sum of all inductances. Here, three inductors are in series. Here, the current through each inductor is the same, but the voltage across each inductor is not the same.

Formula -

L_Total = L₁ + L₂ + L₃

Energy Stored in an Inductor

When a current is drawn through an inductor, an emf is induced in it. This emf opposes the change in current flow through the inductor. Therefore, in order to create a current through the inductor, work needs to be done against this emf by the source voltage.

Formula -

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Uses of Inductors

Transformers
Filters
Chokes
Motors and Generators
Tuning Circuits

Summing Up

An inductor is an electrically passive device that stores energy in a magnetic field when current flows through it. In DC circuits, inductors will first oppose the flow of current, but eventually behave like a wire. In AC circuits, they resist alternating currents, making the current lag the voltage—an effect referred to as inductive reactance, which rises with frequency.

Frequently Asked Questions

Q1. Which laws govern the operation of an inductor?

Inductors are based on Faraday's Law of Electromagnetic Induction and Lenz's Law.

Q2. What is stored in an inductor?

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Q3. What occurs in an AC circuit with an inductor?

In an AC circuit, the inductor causes the current to lag behind the voltage and provides opposition known as inductive reactance, which varies with frequency.