Inductance is a fundamental property of an electrical conductor, which quantifies its ability to store energy in a magnetic field when an electric current is flowing through it. Inductance is typically represented by the symbol “L” and is measured in units called henrys (H).

When a current flows through a conductor, it generates a magnetic field around it. If the current changes, the magnetic field also changes, inducing an electromotive force (EMF) or voltage across the conductor, which opposes the change in current. This phenomenon is known as electromagnetic induction and is the basis for the concept of inductance.

## Henri – Unit of Inductance

The henry (symbol: H) is the SI unit of inductance, named in honor of the American scientist Joseph Henry, who made significant contributions to the field of electromagnetism alongside the British scientist Michael Faraday.

One henry is defined as the inductance of a conductor or a circuit in which an electromotive force (EMF) of one volt is induced when the current through the conductor changes at a rate of one ampere per second (1 A/s). Mathematically, this can be expressed as:

1 H = 1 V·s/A

In practical applications, the henry is often a relatively large unit, so smaller units such as the millihenry (mH) and microhenry (µH) are frequently used. These smaller units are related to the henry as follows:

1 millihenry (mH) = 1 × 10⁻³ henry (H) = 0.001 H 1 microhenry (µH) = 1 × 10⁻⁶ henry (H) = 0.000001 H

Inductance values for various components, such as inductors and transformers, can range from a few microhenries to several henries, depending on the application, design, and construction of the component. By understanding and controlling inductance in electrical circuits, engineers can optimize the performance, efficiency, and reliability of electronic devices and systems.

## Inductance – Examples of Inductors

Inductors come in various shapes, sizes, and inductance values. Here are three examples of inductors with different inductance values:

- Small signal inductor: These inductors are often used in low-power electronic circuits such as filters, oscillators, and signal processing applications. An example of a small signal inductor might have an inductance of 10 μH (microhenries).
- Power inductor: Power inductors are commonly found in power supply circuits, DC-DC converters, and switching regulators. They typically have higher current ratings and inductance values. An example of a power inductor might have an inductance of 100 μH (microhenries).
- High-frequency inductor: These inductors are designed for use in high-frequency applications such as RF (radio frequency) circuits and communication systems. They often have lower inductance values and are optimized for low loss and minimal parasitic capacitance. An example of a high-frequency inductor might have an inductance of 1 μH (microhenry).

These are just a few examples of inductors with different inductance values. The actual inductance value required for a specific application will depend on the circuit design and the desired performance characteristics.