What is a Inductor?

An inductor is an electronic component that can store energy in a magnetic field created by the electric current passing through it.  Another name for an inductor is a choke or a coil.  Electric current through the conductor creates a magnetic flux proportional to the current, and a change in this current creates a corresponding change in magnetic flux which, in turn, by Faraday's Law generates an electromotive force (EMF)(voltage) that opposes this change in current.  Inductors have a similar role to the capacitor, in that, it does with current what a capacitor does with voltage.  An inductor's ability to store magnetic energy is measured by its inductance, in units of henries (L).  Inductance is a measure of the amount of EMF (voltage) generated per unit change in current.  For example, an inductor with an inductance of 1 henry produces an EMF of 1 volt when the current through the inductor changes at the rate of 1 ampere per second.  A Henry represents a large amount of inductance so most inductors are rated in millihenrys (mH), one thousandth of a Henry (10-3 H).  Typically an inductor is a conducting wire shaped as a coil, the loops helping to create a strong magnetic field inside the coil due to Ampere's Law.  The number of loops, the size of each loop, and the material it is wrapped around all affect the inductance.  Inductors are classified as fixed, adjustable, and variable.  All are made either with or without magnetic cores.  The symbol for an inductor on a schematic is shown below.


Inductors have many uses some include; frequency tuning circuits, crossover networks and filtering in power supply circuits.  Inductors encompass some of  the same principles of transformers as a transformers is just two inductors placed close to each other in a contained package.  We will discuss more about transformers in a later article.

There is much more to be learned about  inductors types, composition and the magnetic fields they create.   Additional reading and experimentation can be found in, Greg S. Carpenters Book, "Introduction to Basic Electronics Hands-On Mini Course". For more information on the book, Click Here!

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