Definition of Inductors

Definition of 1.1 inductance:

inductance is the ratio of alternating magnetic flux generated in and around the wire when alternating current passes through the wire. The magnetic flux of the wire is the ratio of the current that produces this magnetic flux.

When a DC current passes through the inductor, only a fixed magnetic field line appears around it, which does not change with time; but when an AC current passes through the coil, the magnetic field lines that change with time will appear around it. According to Faraday's law of electromagnetic induction-magnetic electricity generation, the changing magnetic lines of force will generate an induced potential at both ends of the coil, which is equivalent to a "new power supply". When a closed loop is formed, this induced potential generates an induced current. It is known from Lenz's law that the total amount of magnetic lines of force generated by the induced current should try to prevent the change of the original magnetic lines of force. Since the original change of magnetic field lines comes from the change of the external alternating power supply, the inductance coil has the characteristic of preventing the current change in the AC circuit from the objective effect. Inductive coils have similar characteristics to the inertia in mechanics. They are electrically called "self-induction". Sparks will occur at the moment when the knife switch is pulled open or the knife switch is turned on. This is the phenomenon of self-induction. Caused by high induced potential.

In short, when the inductance coil is connected to the AC power supply, the magnetic lines of force inside the coil will change with the alternating current, causing the coil to continuously generate electromagnetic induction. The electromotive force generated by the change of the current of the coil itself is called "self-induced electromotive force".

It can be seen that the inductance is only a parameter related to the number of turns, size, shape and medium of the coil. It is a measure of the inertia of the inductor coil and has nothing to do with the applied current.