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Inductors may be small, but their impact on electronic circuits is enormous. These passive components can store energy in a magnetic field, which is valuable in the world of electronics. They play a critical role in filtering, amplifying, and generating signals, ensuring a circuit remains stable and functional. Power electronics, telecommunications, and information technology rely on the presence of inductors to deliver reliable and efficient performance. Many electronic devices we use daily would not exist without these fantastic components. So the next time you power up your favorite gadget, take a moment to be thankful for the humble inductor that made it all possible.



Construction of Inductors

Inductors are made up of a coil of wire wound around a core material, which can be air, iron, ferrite, or another magnetic material. The coil is made of a conductive material such as copper or aluminum. Depending on the application, it has a specific number of turns, ranging from a few to several thousand. The coil’s diameter, length, and shape can also vary depending on the desired inductance value and the specific circuit requirements.

The core material used in an inductor can affect its performance. For example, air-core inductors are useful for high-frequency operation applications, as they offer lower losses and higher Q-factor. On the other hand, iron-core inductors are valid for applications requiring a high level of inductance.

Operation of Inductors

Inductors are fascinating devices that operate on the principle of electromagnetic induction. These small but mighty components generate a magnetic field when an electrical current flows through them, storing energy in magnetic flux. When the current suddenly stops or changes direction, the magnetic field collapses and induces a voltage in the coil. This phenomenon is what makes inductors such valuable tools in countless electrical applications. Thanks to their ability to resist changes in current flow, inductors are often called “inductive loads.” From household electronics to high-tech industrial machinery, inductors play a crucial role in keeping our world connected and powered.

How Inductors Work

According to the right-hand rule, when current flows through a conductor, it generates a magnetic field around the conductor. If the conductor is coiled into a spiral shape, the magnetic fields generated by each coil turn combine to create a stronger magnetic field proportional to the number of turns. According to Faraday’s law of induction, when a magnetic field changes, it generates a voltage in the coil that opposes the change.

This phenomenon is known as self-induction and is the basis for how inductors work. An inductor stores energy in the form of a magnetic field when current flows through it, and it releases this energy when the current changes. The inductor’s ability to store energy in the form of a magnetic field is measured in henries, which is the unit of inductance.

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Inductor. (Image Source: jultud/Shutterstock)

Basic Properties and Characteristics of Inductors

Inductors have several properties and characteristics that are important to understand when working with them:

  1. Inductance: Inductance refers to the ability of an inductor to store magnetic energy and is denoted in units of henries (H). A handful of factors, such as the number of windings, the size and shape of the coil, and the type of core material, determine it. All these elements strongly impact how effectively an inductor stores energy when exposed to changing currents. Additionally, other characteristics come into play when considering cost, convenience, or performance metrics related to electrical circuits. Thus all variable inductors are unique in their applications, making a selection for usage critical for device optimization.

  2. Impedance: Inductors present an interesting effect on AC. When voltage fluctuates over time, impedance is introduced by the inductor, increasing in proportion to frequency and the inductance value of the inductor. As such, inductors can be used to design filters for circuits. These filters block out specific frequencies depending on what combination of capacitors and inductors the engineer selects. Using care and skill, engineers can ensure a circuit responds as desired.

  3. Current: In an AC circuit, the current passing through an inductor lags ninety degrees behind the applied voltage. This phenomenon is known as phase shift and results from the inductor’s capability to store energy in its magnetic field. Through this process, a certain quantity of energy can be discharged to maintain a preset magnitude of current flowing through it constantly. In action, an increasing field increases opposition in the device, leading to a current constrained by time constraints spanning over multiple cycles and resulting in a delayed response to any changes of voltage abnormality or change resulting from switching operations. Thus, steadying itself for proper operation within any dynamic state.

  4. Saturation: Inductors, in the face of excessive magnetic field strength, can become ‘saturated’—meaning they are no longer able reaction linearly to the amount of induced voltage. This saturation can drastically reduce inductance and compromise signal integrity. The impacts of such issues have piqued the interest of several electrical engineers who strive to combat these distortions and reproductions to make circuits more precise.

Applications of Inductors

Inductors are used in various electronic circuits, including power supplies, filters, oscillators, and amplifiers. Some typical applications of inductors include:

  1. Power Supplies: Inductors play a crucial role in power supplies by filtering out undesirable noise and ripple in the DC output voltage. Functioning alongside capacitors, they form LC filters that effectively remove high-frequency noise, providing a smooth output voltage. Using inductors in power supplies is vital for electronic devices that require stable, reliable power. With their ability to suppress unwanted electrical signals, both inductors and capacitors work together to ensure the efficient functioning of electronic products. The importance of inductors in power supplies cannot be understated, as they are crucial in guaranteeing the uninterrupted operation of electronic equipment.

  2. Filters: Inductors are a vital component in electronic devices that help filter out unwanted frequencies from a signal. These humble components work with capacitors to create bandpass, low-pass, or high-pass filters. The result is a signal that passes or blocks specific frequencies, depending on the filter configuration. Inductors are found in various applications, from audio and video equipment to power supplies and communication systems. High-quality inductors are essential to maintaining signal integrity and precision in these applications. By selectively attenuating specific frequencies, inductors help ensure that the desired signals get through with minimal interference. With their ability to enhance the signal fidelity and protect against unwanted noise and distortion, inductors are indispensable in modern electronics.

  3. Oscillators: Inductors are a crucial component in oscillator circuits, as they play a significant role in generating stable frequencies. By working in tandem with capacitors to form LC resonant circuits, inductors enable circuits to oscillate at a precise frequency. Producing oscillation at a specific frequency is critical in many electronic devices, from simple radio receivers to complex communication systems. Whether you’re a seasoned engineer or just starting, understanding the importance of inductors is essential for success in electronics. 

  4. Amplifiers: Inductors are used in amplifiers to match the circuit’s impedance and block unwanted frequencies. They are often used with resistors and capacitors to form matching networks that optimize the signal transfer and frequency response.

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Inductor. (Image source: Ladislav Kubeš /KPixMining)

Calculations of Inductors

The inductance of an inductor is measured in henries (H). The inductance value depends on the number of turns in the coil, the coil’s cross-sectional area, and the core material’s permeability. The inductance can be calculated using the following formula:

An inductor’s inductance (L) is measured in henries (H) and depends on the number of turns in the coil, the cross-sectional area of the wire, and the permeability of the core material. The inductance can be calculated using the following formula:

L = (N^2 x µ x A) / l


  • L = inductance in henries (H)
  • N = number of turns in the coil
  • µ = permeability of the core material (in henries per meter or H/m)
  • A = cross-sectional area of the wire (in square meters or m^2)
  • l = length of the coil (in meters or m)

The inductance of an inductor can also be affected by factors such as the physical dimensions of the coil, the spacing between the turns, and the shape of the core material. For example, a toroidal core with a uniform cross-sectional area may produce a more stable and predictable inductance than a non-uniform cross-sectional area.

The impedance of an inductor (ZL) is proportional to the frequency of the AC signal passing through it and is given by the following formula:

ZL = jωL


  • ZL = impedance of the inductor in ohms (Ω)
  • j = imaginary unit (equal to the square root of -1)
  • ω = angular frequency of the AC signal (in radians per second or rad/s)
  • L = inductance in henries (H)


Inductors are essential components in many electronic circuits, and their unique properties and characteristics make them ideal for applications such as filtering, amplification, and signal generation. Understanding the construction, operation, applications, and calculations of inductors can help engineers and hobbyists design and troubleshoot circuits more effectively and efficiently. By using inductors correctly, it is possible to achieve the desired circuit performance and optimize the energy efficiency and reliability of the system.

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