What is an electric coil

An electric coil is a passive component made of a conductor wound into a spiral, usually copper. Its main function is to store energy in the form of a magnetic field when an electric current passes through it. Coils can be constructed without an internal core, in which case the magnetic field forms directly in the air, or they can include a solid core made of materials such as iron or ferrite. The presence of a solid core concentrates and strengthens the magnetic field, increasing inductance and improving the component’s efficiency in specific applications. Due to their versatility, coils are used in a wide range of electrical and electronic devices, from radios and televisions to motors, transformers, and communication systems.

How an electric coil works

The operation of an electric coil is based on the principle of electromagnetic induction. When an electric current flows through the coil’s winding, a magnetic field is generated around the conductor. This field stores energy and opposes any change in the current, a phenomenon known as self-induction. To understand how a coil behaves in different circuits and applications, it is important to analyze several key parameters that determine its performance: inductance, internal resistance, quality factor, operating frequency, and core influence.

Inductance (H)

Measures the coil’s ability to store energy in the magnetic field. It is the main parameter that defines how the coil reacts to current changes and its behavior in electrical circuits.

Internal resistance

The copper wire of the coil presents some resistance, which affects energy dissipation and the overall efficiency of the component.

Quality factor (Q)

Indicates the coil’s efficiency and its ability to operate in resonant circuits. A high Q means that the coil loses little energy and better maintains oscillation in LC circuits.

Operating frequency

Inductance and resistance determine the coil’s behavior at different frequencies, which is fundamental in filters, radio-frequency circuits, and high-frequency applications.

Core influence

The presence of a core concentrates the magnetic field and increases inductance, improving the coil’s efficiency in practical applications such as transformers, power inductors, and resonant circuits.

Types of electric coils

Electric coils can be classified in several ways, but here we will focus on their classification according to core type, as this factor greatly influences their behavior and applications. Each core type grants specific properties that make the coil more suitable for certain uses in electronic circuits and devices.

Air-core coil

These coils have no solid core; the magnetic field forms only in the air. They are easy to construct and are used where low inductance and high frequency are required, such as in antennas and RF filters.

Iron-core coil

These use an iron core to concentrate the magnetic field, significantly increasing inductance. They are widely used in transformers, power inductors, and applications where more energy storage is needed.

Ferrite-core coil

The ferrite core combines high magnetic permeability with low losses at high frequencies. These coils are common in switching power supplies, RF inductors, and communication systems.

Powdered iron core coil

These cores provide a balance between high inductance and low hysteresis loss. They are used in power applications and DC filters, offering stability against saturation.

Applications of electric coils

Electric coils generate and store magnetic fields, and their behavior directly influences the operation of the circuits and devices they are part of. Thanks to these properties, they are used in a wide variety of both electronic and electromechanical applications.

Applications in circuits and electronics

They are used in transformers, power inductors, current filters, and resonant circuits, as well as in antennas and communication systems.

Applications in electromechanical devices

They play an essential role in switched-mode power supplies, electric motors, and other electromechanical devices, where their ability to generate controlled magnetic fields is fundamental.

Core and design influence

The type of coil and core material determine its suitability for each application. For example, air-core coils are ideal in high-frequency circuits, while iron or ferrite-core coils are used in power applications and transformers. This differentiation is key to understanding how they adapt to different practical needs in modern electrical engineering.