Features of Magnetic field lines

- Nov 02, 2017 -

The magnetic field lines are defined as lines that are tangent to the magnetic induction intensity, and the direction of the magnetic induction intensity is the same as the direction of the magnetic field lines, which is proportional to the density of the magnetic field lines. Understand the basic characteristics of magnetic lines is to master and analyze the basis of magnetic circuit.


Theory and practice have shown that the magnetic field lines have the following basic characteristics:

1. Magnetic field lines always start from the N pole, into its nearest S pole, and form a closed loop. This phenomenon is called magnetic flux continuity theorem in electromagnetics, described by the Maxwell equation as:

V.B = 0 (4-1)

The Gaussian law, also known as the magnetic field, indicates that the divergence of any magnetic field is zero, that is, the net flux through any closed surface is always 0 and the magnetic field lines are always closed.


2. Similar to the current, the magnetic field lines always take the path of the smallest magnetoresistance (the maximum permeability), so the magnetic field lines are usually linear or curved, there is no right-angle bending of the magnetic field lines.


3. Any two co-magnetic lines are mutually exclusive, so there is no intersecting magnetic field lines.


4. When the magnet material is not saturated, the magnetic field lines are always perpendicular to the polar surface of the ferromagnetic material. When the ferromagnetic material is saturated, the behavior of the magnetic field lines in the ferromagnetic material is the same as in non-ferromagnetic media such as air, aluminum, copper, etc.

Since the magnetic field lines have such basic characteristics, the magnetization state of the medium depends on the magnetic properties and geometries of the medium. Obviously, in general, the media are in a non-uniform magnetization state, that is usually the internal magnetic field lines are in a state of curve and uneven distribution; In addition, due to the existence of electricity in the natural insulator, but there is no magnetic insulator, So that the usual magnetic circuit exists magnetic flux leakage. The medium is in the non-uniform magnetization state and the magnetic circuit there are two characteristics of magnetic flux leakage, it is decided that the exact calculation of the magnetic circuit is very complex.


Article from NdFeB Industry Network

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