Question

Define the term “Self Inductance” of a coil. Write its SI unit.

Answer 1

Hint: It is related to a current carrying conductor or wire, it is a self-developed feature of a conductor when current is passed through it. There are different ways in which a coil gets self-inducted.

Complete answer:
Self-inductance is a particular form of electromagnetic induction. It is defined as the induction of a voltage in a current-carrying wire, solenoid, conductor when the current in the wire itself is changing. In the case of self-inductance, the magnetic field that is created by fluctuating or changing the current in the circuit induces a voltage. Hence the voltage is called self-induced voltage.

The inductor is an element of a circuit possessing the property of inductance . In circuit diagrams, a coil or wire is usually used to indicate an inductive component. On taking a closer look at a coil it will help understand the reason that a voltage is induced in a wire carrying a changing current. The alternating current running through the coil creates a magnetic field in and around the coil that increases and decreases as the current changes. The magnetic field forms concentric loops that surround the wire and join to form larger loops that surround the coil. The expanding current and the magnetic field in one loop also coincides with other loops inducing current in them also.
The SI unit of “SELF INDUCTANCE” is henry(H).

Note: The concept of induction is a bit confusing, in general it is a type of current that does not generate due to potential difference (that is voltage) but due to presence of a constant changing magnetic field that induces the current in the conductor.

In this diagram we see when the magnet is moving current is induced in the coil resulting in the illumination of the bulb.

In this diagram, we see when the magnet is not moving no current is induced in the coil.