What is an Inductor?

  • Inductor is an electrical component that stores energy in the form of magnetic field.
  • An inductor is a passive electrical component that opposes sudden changes in current. Inductors are also known as coils or chokes.
  • The inductor can be made through conducting wire as a coil. Inductors slow down current surges or spikes by temporarily storing energy in an electro-magnetic field and then releasing it back into the circuit.
  • The inductance of an Inductor is highly dependable on multiple factors, such as number of turns of wire, the spacing between the turns, no of layers of turns, type of core materials, its magnetic permeability, size, shape etc.
  • The electrical symbol for an inductor is L
  • The measurement unit of an inductor is Henry [H].
  • It blocks any changes in current flowing through it.

How does an Inductor work?

Difference between two terminologies, Magnetic Field and Magnetic Flux.

During the Current flow through the conductor, a magnetic field is generated. These two things are linearly proportional. Therefore, if the current is increased, so the magnetic field will also increase. This magnetic field is measured in the SI unit, Tesla (T). Now, what is Magnetic Flux? Well, it is the measurement or quantity of the magnetic field which passes through a specified area. Magnetic Flux also has a unit in SI standard, it is Weber.

So, as of now, there is a magnetic field across inductors, produced by the current flowing through it.

To understand further, understanding of Faraday’s law of inductance is required. As per Faraday’s law of inductance, the generated EMF is proportional to the rate of change of the magnetic flux.

VL = N (dΦ / dt)

where N is the number of turns and Φ is the amount of flux

Construction of an Inductor

One generic, standard inductor construction and working can be demonstrated as a copper wire wrapped tightly across a core material. In the below image, copper wire is closely wrapped across a core material, making it a two terminal passive inductor.

When the current flow through the wire, the electromagnetic field will develop across the conductor and electromotive force or EMF will generate depending upon the rate of change of the magnetic flux. So, the flux linkage will be Nɸ.

What is the Self Resonant Frequency of an inductor?

The self resonant frequency of an inductor is the frequency at which the parasitic capacitance of the inductor resonates with the ideal inductance of the inductor resulting in an extremely high impedance. 
 
The parasitics of an inductor vary based on the type of inductor – wire wound inductor, multi-layer inductor, conductive film inductor etc.

Use of Inductor

With the help of inductors, the tuning circuits can select the desired frequency.
The capacitors along with the inductor are used in various electronic devices such as radio tuning circuits, a television in order to modify the frequency and help to select within multiple channels of frequency.

Inductors when combined with capacitors will be used as filters.

The input signal’s frequency while entering the circuit is limited by the use of these filters. With the increase in the frequency of supply, the inductor’s impedance increases.

Inductors can store energy for a small period of time because the energy which is being stored as a magnetic field will be gone when the power supply is removed. Uses of inductors can be seen in computer circuits where power supplies can be switched.

Types of Inductors

Inductors for Noise Filtering

Inductors for Energy Storage 

Application Notes

Inductor Selection Tool