The physics behind inductors

In electrical circuits, there are many different components. Commonly known ones would be batteries, resistors, or light-emitting diodes (also known as LEDs). Another electrical component that may not be as common to hear about would be the inductor. In this article, we will explore what an inductor is, what it does, and the physics behind how the inductor is able to do its job!

What is an inductor?

An image of an inductor in the shape of a toroid (Matsusada Precision Inc, 2022)

An inductor is a component that is able to store electrical energy and release this energy back into the circuit when needed such as in power supplies. The inductor is thus able to resist sudden changes in the current and allows current in the system to not change so suddenly. 

Inductors come in many different forms, such as a solenoid (a cylinder-like shape) or a toroid (a ring-like shape). Despite its many shapes, the inductor is actually just a piece of wire coiled to form its appearance. It looks like an electromagnet, but they have different functions! Unlike an electromagnet, an inductor focuses on the electrical properties of electromagnetism while the electromagnet focuses on behaving like a magnet (Wikipedia Contributors, 2019). Similar to an electromagnet, some inductors would be coiled using a conductive wire, while others may have cores inside the wound conductors (Matsusada Precision Inc, 2022). 

How does an inductor work?

To understand how an inductor works, we would need to understand the relationship between electricity and magnetism. Did you know, when a current goes through a piece of wire, there is a magnetic field that is generated? However, this magnetic field due to a current-carrying straight wire is very small, so coiling the wire into a cylinder-like shape (a solenoid) would enhance the magnetic field. This is actually how electromagnets are created!

An image of an electromagnet (www.iqsdirectory.com., n.d.), where the blue lines represent the magnetic field lines of the electromagnet

According to Faraday’s Law, a changing magnetic flux - which refers to the total magnetic field that passes through a given area - causes an induced electromotive force. Now, we know a current passing through a wire is able to create a magnetic field, but this magnetic field is not changing as the current is steady. As such, if we make the current to be fluctuating, there will be a changing magnetic flux due to the magnetic field also changing. Due to this changing magnetic flux, there will be an electromotive force that is induced due to the magnetic field. By Lenz’s Law, this electromotive force induced is in the opposite direction of the changing magnetic field. 

Relating back to the inductor, the above gives the answer as to how inductors are able to resist sudden changes in the current: As the current changes, there will be an electromotive force generated in order to resist this change. For instance, in a circuit with an inductor, a battery and a resistor in parallel, if the switch is suddenly opened and the battery no longer supplies power to the circuit, there is a fall in the current, causing the back electromotive force to increase so as to resist the falling current. This actually causes the circuit to still have current flowing despite the switch opening! 

Conclusion 

In conclusion, inductors are basically a coil of wire that is able to resist sudden changes in the current flow of a circuit. They use the concepts of electromagnetic induction to ensure that current in a circuit does not drop or rise suddenly, 

If you would like to better understand how the inductor works in a circuit or watch an animation of the above explanation, you may watch this video (The Engineering Mindset, 2019) to find out more!

Works Cited

Matsusada Precision Inc (2022). What is an inductor (coil)? Principle and Roles. [online] Matsusada Precision. Available at: https://www.matsusada.com/column/words_inductor.html [Accessed 7 May 2025].

The Engineering Mindset (2019). Inductors Explained - The basics how inductors work working principle. [online] Youtube. Available at: https://youtu.be/KSylo01n5FY?si=5DONa0xms9DGa8b5 [Accessed 11 May 2025].

Wikipedia Contributors (2019). Inductor. [online] Wikipedia. Available at: https://en.wikipedia.org/wiki/Inductor [Accessed 7 May 2025].

www.iqsdirectory.com. (n.d.). Inductors and Inductor Coils: Types, Applications and Principles. [online] Available at: https://www.iqsdirectory.com/articles/electric-coil/inductors-and-inductor-coils.html [Accessed 8 May 2025].