What is inductance and what is its application!

Do you know what inductance is? To better understand this physical quantity called inductance, it is necessary to know its characteristics and behavior in electrical circuits. Know the types of inductors, how to read the value of the inductance present in the commercialized inductors, check short-circuit or open-circuit tests at the inductor terminals and the applications of the inductors in the various segments of commerce and industry.

Definition of inductance

The passage of electric current in a straight conductor, for example, the electrical cable in your home, is capable of producing a magnetic field around it. When using a copper conductor in the shape of turns it is possible to determine a physical quantity existing in devices called inductors, such quantity is called the inductance.

The variation of the electric current in the inductor causes changes in the flow of the magnetic field lines that cross the turns, and consequently, there is a potential difference between the coil terminals. It is important that you understand that only by using an alternating current, or opening and closing a switch in an electrical circuit, is it possible to generate this potential difference in the inductor. Therefore, in pure direct current circuits, this current variation does not occur, and the inductor starts to behave as a short circuit in the permanent regime. The equation that relates these quantities is:

Induced electromotive force (EMF)


∈: It is the potential difference at the coil terminals

L: Inductance measured in Henry (H)

Δi / Δt: It is the variation of the electric current in time

Inductance characteristics

The inductance depends on the geometric characteristics of the loop, that is, the inductance depends on the radius, the number of turns, and the permeability of the material that fills the core of the inductor. It is important to emphasize that to increase the inductance intensity in a coil, it is possible to choose to increase the number of turns of the turns, or even increase the area of ​​the inductor core.

Types of inductors

Like resistors and capacitors, inductors can be defined as fixed or variable. Fixed inductors are manufactured in various shapes and sizes, in general, the size of an inductor is dependent on the type of construction, current specification and the characteristics of the core used.

Some examples of fixed inductors.

When using the ferrite core inductor, it is possible to increase the inductance compared to inductors of the same size, however, with scores produced with other materials. Variable inductors, as the name implies, allow their inductance to be varied, that is, these devices have slits at the ends of the nucleus, and when rotated in the inner direction of the nucleus, they cause the interaction of the ferromagnetic nucleus, thus raising , the intensity of the magnetic field and the level of inductance.

Inductor with variable inductance.

Inductor labeling and testing

Some inductors have high dimensions and their identification is printed on the device body. However, some inductors are much smaller and there is no room for printing this identification. Thus, for color-coded inductors, a color code similar to that used for resistors is used .

To measure or even test an inductor it is advisable to use an inductance meter, however, if it is not possible to obtain it, an ohmmeter can be used to check, for example, if there is a short between the windings or even a circuit Open.

When reading an open circuit, the ohmmeter has a high or infinite resistance value, in turn, in a short circuit, the verification becomes more complicated, since some inductors have a relatively small winding resistance. The short between the windings and the core can be seen by placing one ohmmeter wire on the loop and the other on the core, with this, the ohmmeter will indicate a zero ohm reading.

Do you know how to measure cable continuity with the multimeter? The video below will teach you how to correctly use the multimeter for measuring cable continuity!

Inductor applications

Air core inductors: High frequency applications;

Toroidal type inductors: Used in transmission lines to filter transients and reduce electromagnetic interference, applied to various appliances;

Cylindrical type inductors: Used in high current transmission lines;

Line delay type inductors: Used in color television receivers, to correct time differences between color signals;

Common mode cylindrical type inductors: Used in AC line filters, and battery chargers.

We hope you have understood the difference between the main types of inductors and the applications of this device in the different areas of electronics. If you have any questions on this matter, leave it in the comments and we will be happy to answer them!