Self-inductance, often simply referred to as inductance, is a fundamental property of an electrical component known as an inductor. It is the ability of an inductor to oppose changes in the flow of electric current through it by inducing a voltage in the opposite direction. Self-inductance is a result of Faraday's law of electromagnetic induction and is a crucial concept in electromagnetism and electronics.

Key points about self-inductance:

1. Opposition to Current Changes: When the current through an inductor changes, the inductor generates a voltage (an electromotive force, EMF) in response to this change. This induced voltage opposes the change in current, and the inductor resists any sudden or rapid changes in current flow.

2. Self-Inductance Coefficient (L): The self-inductance of an inductor is quantified by a property known as self-inductance coefficient, usually represented by the symbol “L.” The unit of inductance is the henry (H), named after Joseph Henry, an American scientist. One henry is equivalent to one volt-second per ampere (V·s/A).

3. Mathematical Relationship: The voltage induced in an inductor due to a change in current is directly proportional to the rate of change of current and the self-inductance of the inductor. Mathematically, this relationship can be expressed as:

 V = L * dI/dt

 Where:
 - V is the induced voltage (in volts).
 - L is the self-inductance of the inductor (in henrys).
 - dI/dt represents the rate of change of current (in amperes per second).

4. Energy Storage: In addition to opposing changes in current, inductors also store energy in their magnetic fields. The energy stored in an inductor is proportional to the square of the current and is given by the formula:

 Energy (W) = 0.5 * L * I²

 Where:
 - W is the energy stored (in joules).
 - L is the inductance (in henrys).
 - I is the current (in amperes).

5. Applications: Inductors with their self-inductance property are used in various electrical and electronic applications. They are commonly used in filter circuits to block or pass specific frequencies, in transformers for energy transfer, and in many electronic devices to control current and voltage.

Self-inductance is a fundamental concept in electromagnetism and is a key parameter in designing circuits and systems that involve inductors, helping control and manage the flow of electrical energy and signals.