What is inductor? and its types

What is inductor? and it’s unit

Inductors are an electrical component that has two terminals and they have the ability to store energy in a magnetic field only when an electric current flows through it. The inductor can be called a conductor that is wound into a coil and when the electricity flows through it from left to right it could generate a magnetic field in a clockwise direction. When the current flows through the inductor the generated magnetic field creates an electromotive force in the conductor and the polarity of the induced voltage opposes the change in current that created it. When electricity passes through the inductor initially there will be a huge resistance until its magnetic field is up and if the power stops flowing the magnetic field will collapse into the inductor forcing the electricity forward until the field has completely collapsed. Most of the inductors have a magnetic core that is made of iron or ferrite inside a coil which will increase the magnetic field and therefore the inductance will increase too. The unit of measurement for an inductor is henry and the symbol for inductance is L.

What is the difference between the inductor and inductance

Inductance is the property of an electrical device to resist the change in the flow of current. It is the process of inducing an EMF only when there is a change in current occurs. Inductors are devices that can create inductance they are a passive device that has two –terminals.

How does an inductor charge or discharge

If the current through the inductor increases, it drops the voltage opposing the direction of electron flow and acts as a power load. This can be considered as the charging of the inductor and it is because an increasing amount of energy is being stored in its magnetic field. The voltage will drop in case if the current through the inductor decreases and the voltage drop will help the direction of electron flow acting as a power source. This process can be called as the discharging of the inductor because the stored energy is decreasing as the energy is released from its magnetic field

What are the properties of an inductor

  • They act as a short circuit at a steady state when connected to a DC voltage or current source
  • Current through an inductor will be continuous, there won’t be any changes to the current but there will be changes in voltage across the inductor
  • Inductor reacts against the changes in current by dropping the voltage in polarity to oppose the change.
  • Inductor will act as a load when there is an increasing current, it drops voltage while it absorbs energy
  • It acts as a source when there is a decreasing current, creating voltage as it releases the stored voltage.
  • Inductors can store energy in the form of a magnetic field and this process is called inductance

How does an inductor work

The induction process is described by Faraday, his law states if a conductor is moved through a magnetic field. So that it cuts the magnetic flux of lines a voltage will be induced across the conductor. The induced voltage will be high if the number of flux line cuts is high or by stronger magnetic field strength.

What are the types of inductors

Air core inductors

In air-core inductors it does not use a magnetic core made of ferromagnetic material instead of that it uses the coil which is wounded on plastic, ceramic or other non-magnetic forms or those which have only air inside the windings. An advantage of air-core coil-over ferromagnetic core coil is that air core coil doesn’t have any core loss or energy loss and because of this feature, they are used in high frequencies. The major disadvantage of an air-core coil is that the coil is not rigidly supported and mechanical vibration in the winding can cause vibration in the inductance. The inductance is not affected by the current it carries.

Iron core inductor

These inductors are used in places were low space inductors are needed these inductors have high power and high inductance value but limited in high-frequency capacity these are used in audio equipment. These inductors have very limited applications.

Ferrite core inductor

This type of inductor is referred to as a ferromagnetic material. They exhibit magnetic property they consist of mixed metal elements of iron and other elements of crystalline structures. Ferrite core inductor has non-conductive ceramic material for higher frequency applications. Ferrite core inductors have low resistance with high inductance they can be used for high frequencies.

Multilayer ceramic inductors

As the name indicates this inductor consists of many layers by adding an additional layer of coiled wire that is wounded around a center core of inductor gives multi-layer inductor. Generally, for more turns more inductance will be there. In this type of inductor, not only the inductance increase but also the capacitance between the wires increase the main advantage of this inductor is by giving lower operating frequency we will get higher inductance.

Toroid type inductors

These inductors are of small size, very lightweight. It is a doughnut-shaped ferrite core that reduces radiated electromagnetic interference. Because of their symmetrical structure, there will only be less magnetic flux escape outside the core. The core is created in a closed magnetic field to get a higher magnetic field and inductance.

Molded inductors

The inductors which are set inside a plastic or ceramic core is called as molded inductors. These inductors are in the shape of a cylinder or bar.

Laminated core inductors

Low-frequency inductors are made with laminated cores to prevent eddy currents the core will be made up of stacks of thin steel sheets or laminations which are parallel to the field, with an insulating coating on the surface. Lamination will help to reduce resistance loss.

Coupled inductors

These types of inductors can share a magnetic path and can influence each other. These inductors are used as transformers to step-up or step-down voltage, and they are also used to provide isolated feedback and in applications were mutual inductance is needed.

Power inductors

They are available in a wide variety of power levels from inductors which can handle a few amps to hundred amps. Power inductors are subjected to a large amount of current and because of this, they can create a large magnetic field. Magnetically shielded inductors are used to prevent these magnetic fields from inducing noise in other parts of the circuit.

RF inductors

Radiofrequency inductors are high-frequency type inductors they are designed to operate at high frequency. These inductors have higher resistance and lower current ratings. Mostly these inductors have air-core because while using other material energy loss will be high and it will reduce the operating frequency of the inductor.


A choke is an inductor which can block high-frequency pulse while letting lower frequency pulse through and they are named so because of their ability to choking off or blocking of the high-frequency signal. There are two types of chokes power and RF chokes. In an electrical circuit, the higher frequency blocking will be of alternating current and the lower frequency which is allowed to pass will be direct current.

What are the applications of inductors

  • It is used as an energy storage device in many switched-mode power supplies to produce DC current
  •  Inductors are used in electrical transmission systems were they are used to limit switching currents and fault currents
  • An inductor can function as a low pass filter
  • Inductors can be used as sensors to sense a magnetic field
  • Inductors are widely used in analog circuit and signal processing
  • They are used as an energy storage device in switched-mode power supplies to produce DC current
  • An inductor can be connected to a capacitor to form a tuned circuit


post-graduate in Electronics & communication.

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