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What does "magnetic field" and "magnetic flux" mean?

In literature, the terms "magnetic field", "magnetic flux" and "flux density" are often used as synonyms. This is not correct because they are different physical values, but they are closely linked. Find out below how these values differ from each other.
Table of Contents

Magnetic field / Magnetic field strength (H)

The magnetic field is a field of electromagnetic energy that transfers the forces of a magnet.
The magnetic field is often depicted with field lines. It is also possible to make it visible with iron filings on a sheet of paper with a magnet underneath.
By definition, magnetic field lines always run from the north to the south pole of a magnet and from there through the magnet back to the north pole, which creates a closed circle.
The magnetic field is abbreviated with the letter H and is measured with ampere per metre.

Magnetic flux density B

The magnetic flux density B describes the density and direction of the field lines that run through an area A. The denser the field lines, the larger the magnetic flux density, which is measured in tesla (T).

Magnetic flux Φ

The magnetic flux Φ is the magnetic flux density which runs through an imagined area.
If the field lines run in a straight line (e.g. between the poles of a horseshoe magnet), the magnetic flux Φ through a certain area A which runs vertically to the flux can be calculated as follows:
Φ = B•A
The unit is Tm².