When there is an electric current in the coil, a magnetic field is generated around the coil.
When the current changes in the coil, the surrounding magnetic field also produces a corresponding change, this change in the magnetic field can cause the coil itself to generate induction electromotive Force (EMF) (electromotive force to represent the ideal power source components of the end voltage), this is the self inductance. The electronic components, which have a certain number of turns and can produce a certain amount of inductance or mutual inductance, are often called inductance coils. In order to increase the inductance value, improve the quality factor, reduce the volume, often add ferromagnetic material made of iron core or magnetic core. The basic parameters of inductor are inductance quantity, quality factor, intrinsic capacitance, stability, current and frequency of use.
The inductor, which consists of a single coil, is called a self inductance device, and its self inductance is also called the self inductance coefficient.
Transformer When two inductance coils are close to each other, the magnetic field change of one inductance coil will affect the other inductance coil, the effect is mutual inductance. The size of the mutual inductance is determined by the degree to which the inductance of the inductor coil is coupled with the two inductance coils, and the components made of this principle are called transformers.