Inductors are components that can convert electrical energy into magnetic energy and store it. The structure of inductor is similar to that of transformer, but there is only one winding. The inductor has a certain inductance, which only blocks the change of current.

If the inductor is in the state of no current passing, it will try to prevent the current from flowing through it when the circuit is connected; If the inductor is in a state of current flow, it will try to maintain the current when the circuit is disconnected. Inductor is also called choke, reactor and dynamic reactor.

Inductors are generally composed of skeleton, winding (winding), shielding cover, packaging materials, magnetic core or iron core, etc. magnetic core and winding are the soul of inductance.

From the perspective of physics, there are many magnetic domains in the magnetic core, which can be understood as very small magnets, and each small magnetic domain will produce a certain magnetic field. When the magnetic core has not been magnetized (i.e. when no current passes through), due to the disordered arrangement direction of the internal magnetic domains, the magnetic fields generated by the magnetic domains cancel each other, so the whole magnetic core is not magnetic externally.

In this process, it can be considered that the magnetic domain does work under the action of the magnetization field, that is, it converts the magnetic field energy into magnetic torque and saves it, and the manifestation is the magnetic field intensity B.

It is with such energy conversion that the role of inductance in the circuit is brought into full play:

Energy storage: the current flowing in the coil generates a magnetic field, which then generates current. In this way, the coil can store electric energy into magnetic energy. This is achieved through the inductance of the coil.

Signal sorting: remove interference signals and let only the required signals pass. According to the different signal frequency, the role of the coil is also different.