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4.5:

Inductors

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Electrical Engineering
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JoVE Core Electrical Engineering
Inductors

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Inductors, often referred to as coils or chokes, play a crucial role in various electronics and power systems.

In essence, any conductor through which an AC current flows inherently possesses inductive properties and could be categorized as an inductor.

To enhance the inductive effect, practical inductors are created by winding a conductive wire around a core made of magnetic material.

When a current flows through an inductor, the voltage across it is directly proportional to the rate of change of the current over time. This proportionality constant is known as the inductance of the inductor, and it is measured in henry.

Inductance opposes abrupt changes in the current flowing through it. So, the current through an inductor cannot change instantaneously.

The physical dimensions, core material, and construction of the inductor determine its inductance.

Inductors come in a variety of values and types, ranging from a few microhenrys to tens of henrys.

They can either be fixed or variable, with cores constructed from a variety of materials including iron, steel, plastic, or even air.

4.5:

Inductors

An inductor is a passive component built to store energy within its magnetic field. It can be fabricated by coiling a wire around a magnetic core. When current is permitted to flow through this inductor, it is observed that the voltage across the inductor is directly proportional to the time rate of change of the current. Mathematically,

Equation1

This relationship is expressed using the passive sign convention, where 'L' represents the constant of proportionality, also known as the inductance of the inductor.

The inductance of an inductor is influenced by factors such as its size, the materials used, and the construction method. The unit of measurement for inductance is the Henry (H). Inductance is a measure of the ability of a device to store energy in the form of a magnetic field. Also, it is a characteristic that allows an inductor to resist changes in the current flowing through it.

In addition to being referred to as inductors, these components can also be called coils or chokes. The circuit symbol for an inductor is presented in Figure 1.

Figure1

Figure 2 shows a graphical representation of the relationship between voltage and current for an inductor whose inductance does not depend on the current, also known as a linear inductor.

Figure2

A nonlinear inductor, on the other hand, would not have a straight-line plot, as its inductance fluctuates with the current.

Inductors, akin to capacitors, are commercially available in various values and types. In practical applications, inductors typically have inductance values ranging from a few microhenrys, as seen in communication systems, to tens of henrys, as used in power systems. Inductors can either be fixed or variable, and their core can be composed of various materials, including iron, steel, plastic, or even air.