Self-inductance is a property of an electrical circuit or a component that describes its ability to generate an electromotive force (EMF) in response to a change in the current flowing through it. It is a fundamental concept in electromagnetism and is a key element in understanding the behavior of inductors, which are passive electronic components designed to store and release electrical energy in the form of magnetic fields.
When the current through a coil or an inductor changes, it creates a changing magnetic field around the coil. According to Faraday's law of electromagnetic induction, a changing magnetic field induces an EMF in the same coil or circuit. This induced EMF opposes the change in current that produced it. This effect is known as self-induction.
The self-inductance of a coil or an inductor is represented by the symbol "L" and is measured in henries (H). Mathematically, the self-induced EMF (voltage) "v" across an inductor is proportional to the rate of change of the current "i" flowing through it:
v = -L * di/dt
Where:
"v" is the voltage across the inductor due to self-inductance.
"L" is the self-inductance of the inductor.
"di/dt" is the rate of change of current with respect to time.
The negative sign in the equation indicates that the induced voltage opposes the change in current, following the principle that nature tends to resist changes.
Self-inductance plays a significant role in various electrical and electronic applications, such as inductors used in transformers, motors, generators, and other circuits where energy storage, voltage regulation, and electromagnetic coupling are important.