Magnet basics

Magnetic Flux Density and Magnetic Flux

The two main magnetic field properties of magnets which are normally measured are magnetic flux density and magnetic flux. To explain the difference between the two consider the magnets below:

Magnet A is smaller than magnet B. They both have the same “magnetism”, that is the same amount of total flux. As A has a smaller surface area than B it has a much higher “magnetic strength” or magnetic flux density.

Magnet C and D have different “magnetism” that is they have a different amount of total flux. Magnet D has a much higher magnetic flux, however magnets C and D have the same magnet flux density.

The amount of magnetic flux a magnet displays is a direct result of the material that makes up the magnet. The magnetic flux density is a product of the magnetic flux and the area that this flux is present within.

Measuring each of these characteristics requires the use of a different type of magnetic instrument:

Hirst Technology webpage

Here a few links that should help :-

magnetisation :


gaussmeter background: