Table of Contents
Table of Contents
Variety of inductor forms [1] |
What are Inductors?
An inductor is a passive component with two terminals, typically constructed of a coil of wire surrounding a "core" of some material, usually a magnetic material like iron or ferrite ceramic, or air (supported by plastic if necessary) [2]. Inductors store electrical energy by inducing a magnetic field when current flows through it, hence the name [2]. Inductors resist change in the current flowing through it by either storing or releasing energy from the magnetic field to create an electromotive force (voltage) to oppose the change; this relationship is described by Lenz's law [2]. This effect is known as inductance [4]. Inductors are useful for many different purposes, including blocking high-frequency noise, electronic filters, tuned circuits, and power converters, any time there might be spikes or changes in current that needs to be controlled [3].
Inductance
Inductance is the ability for an inductor to induce voltage as a result of a change in current, and is denoted with L and measured in Henries (singular Henry, symbol H) [4], though most inductors come in values of microHenry or milliHenry. Inductance is quantified by the ratio of voltage to the rate of change of current [4]. This means that increasing the inductance results in a greater resistance to change, which may be beneficial or detrimental depending on its application. The value of an inductor is influenced mainly by the length of the coil, the cross-sectional area of the coil, the number of turns (of wire), and the magnetic permeability of the core [4]. The length of the coil is inversely proportional to the inductance of the coil, but increasing any of the other three factors will increase the inductance [4].
Inductor Construction
Inductors can be made of a variety of materials. The wire that makes up the inductor coil is usually insulated copper, sometimes aluminum [2]. Like mentioned before, increasing the number of turns in the coil increases the inductance, so the diameter and even cross-section of the wire can be important when many turns are necessary.
The other component is the core, whose shape and material influences the form factor and inductance of the component, which determines what applications the inductor is suitable for.
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