Self-Inductance:

Self-inductance is a property of a coil, which induces a counter e.m.f. in it when the current through the coil changes. It is also known as the inductance of the coil. The self-inductance of a coil is denoted by the letter L, and its unit is Henry (H).

Working:

When a current flows through a coil, it creates a magnetic field around it. According to Faraday's law of electromagnetic induction, when the current through the coil changes, the magnetic field around the coil also changes. This change in magnetic field induces a counter e.m.f. in the coil, which opposes the change in current through the coil. This phenomenon is known as self-induction.

Formula:

The self-inductance of a coil depends on the number of turns of wire in the coil, the cross-sectional area of the coil, and the magnetic permeability of the core material. The formula for the self-inductance of a coil is given by:

L = (μN²A)/l

Where L is the self-inductance of the coil, N is the number of turns of wire in the coil, A is the cross-sectional area of the coil, l is the length of the coil, and μ is the magnetic permeability of the core material.

Applications:

Self-inductance is used in various electrical and electronic devices such as transformers, solenoids, inductors, and chokes. These devices are used for various purposes such as voltage regulation, energy storage, filtering, and signal processing. Self-inductance is also used in the ignition system of automobiles, where a spark is generated by a sudden interruption of the current through the coil, which induces a high voltage in the secondary coil.

Conclusion:

Self-inductance is a fundamental property of a coil, which plays a crucial role in various electrical and electronic devices. Understanding the concept of self-inductance is essential for the design and analysis of these devices.