An inductor is an electronic component commonly used in electrical circuits to store and manipulate energy in the form of a magnetic field. It is a passive two-terminal device that consists of a coil of wire wound around a core, usually made of a magnetic material like iron or ferrite. The basic principle behind an inductor's operation is electromagnetic induction.
When an electric current flows through the coil, a magnetic field is created around it. The strength of this magnetic field is directly proportional to the amount of current passing through the coil. When the current through the inductor changes, the magnetic field also changes. This changing magnetic field induces an electromotive force (EMF) or voltage across the inductor, which opposes the change in current.
According to Faraday's law of electromagnetic induction, any change in magnetic flux linked with a coil will generate a voltage in the coil. The induced voltage creates a back EMF that opposes the applied voltage or current. As a result, an inductor "resists" changes in current, leading to its fundamental property: inductance (L), measured in henries (H).
The energy stored in an inductor is proportional to the square of the current passing through it and the value of its inductance. The formula to calculate the energy stored in an inductor is:
Energy (W) = (1/2) * L * I^2
where:
W = Energy stored in the inductor (in joules)
L = Inductance of the inductor (in henries)
I = Current passing through the inductor (in amperes)
When the current through the inductor increases, energy is stored in its magnetic field. Conversely, when the current decreases, the magnetic field collapses, releasing the stored energy back into the circuit. This behavior makes inductors useful in various applications, such as smoothing out voltage fluctuations in power supplies, filtering signals, and storing energy in devices like transformers and chokes.