How Magnetic Cores Increase Inductance

Why does adding a magnetic core to an inductive coil increase the inductance value significantly?

When there is no magnetic core in the coil, a certain current is passed through the coil. According to the principle of electrogenerated magnetism, a magnetic field will pass through the coil, assuming that the magnetic field intensity generated at this time is H.

If there is a magnetic core in the coil at this time, some magnetic domains in the core will be arranged in an orderly manner under the action of magnetic field strength H. These magnetic domains will generate a magnetic field in the same direction as the original magnetic field, which is much larger than H. Therefore, the total magnetic field will increase significantly. The combined magnetic field strength of the two is called B.

This ability to increase the magnetic field has a parameter called permeability µ, B=µ H. The previous explanation is for ease of understanding.

In fact, the rigorous definition of µ is as follows. Under the same conditions, the magnetic induction intensity generated in ferromagnetic media is much greater than that in air media. To characterize this characteristic, different magnetic media are considered with a coefficient µ, which is called the magnetic permeability of the medium and characterizes the magnetic permeability of the material. In the medium, the larger µ, the greater the magnetic induction intensity B in the medium.