Like capacitors and resistors, an inductor is also a passive element. Simply, an Inductor is a twisted wire or coil of electroconducting material. Inductance is the property of an electric conductor or a circuit that opposes the change to a flow of current.

An electric conductor or a circuit element with the property of Inductance is called an Inductor. When there is a change of current in a coil or a twisted wire (inductor), it opposes this change by generating or inducing an electromotive force (EMF) in itself and nearby conducting materials.

Capacitance is the measure of the ability of a conductor to store electric charge i.e. electric field energy. In contrast, Inductance of an electrical conductor is the measure of its ability to store magnetic charge i.e. magnetic field energy.

An inductor stores the energy in the form of magnetic field. As magnetic field is associated with flow of current, inductance is associated with current carrying material. The inductance of a coil is proportional to the number of turns of the coil.

Di-electric materials like plastic, wood and glass have least inductance. But the Ferro magnetic substances (iron, Alnico, chromium ferroxide) will have high inductance.

The unit for inductance is Henry, micro Henry, milli Henry etc. It can also be measured in Weber/ ampere. The relation between Weber and Henry is, 1H = 1 Wb/A.

To understand the inductance of a coil, we should know about Lenz law, which explains us how the emf will induce in an inductor. Lenz’s law states an induced electromotive force that generates a current that induces a counter magnetic field opposing the magnetic field generating the current.
Another definition of Inductance is “The electromagnetic force produced in a coil by applying the voltage of 1 volt, and is exactly equal to one Henry or 1 ampere/ second”.

In other words, for 1 volt of voltage VL and the rate of flow of current is 1 amp/ sec then the inductance of the coil is L, measuring 1 Henry.

The induced voltage in the inductor (coil) is given as

V_L = -L di/dt (volts)

The negative sign indicates the opposing voltage in the coil per unit time (di /dt).

The inductance in a coil is of 2 types, they are

- Self inductance
- Mutual inductance

(to be updated)