Magnets glossary

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Air gap

 Air gap between the magnetic poles of a red power horseshoe magnet 

An air gap is the term used to describe the distance between the two magnetic poles, for example when the magnet has been bent into a horseshoe shape.



 No high temperatures 

Demagnetisation is the process whereby a magnet loses all of its magnetic properties. A magnet can be demagnetised as a result of:

  • Other magnets

  • High temperatures 

  • Electricity

  • Vibration

 Dead magnet 

For information on how to avoid demagnetisation, see the page: How to avoid demagnetising a magnet




An electromagnet has a magnetic field created by electricity. Electromagnets usually consist of copper wire being wound tightly around a ferromagnetic material, which is then supplied with electricity. One of the defining characteristics of an electromagnet is its ability to be turned off and on again.


Ferromagnetic materials

 Ferromagnetic materials: gadolinium, iron, cobalt, and nickel 

Ferromagnetic materials are those which are attracted by a magnetic force. To be ferromagnetic they must contain a element of iron, nickel, cobalt, or gadolinium.


For more information on ferromagnetic materials, see the page: What materials can magnets attract?



 Basic magnetic discs with keepers in between 

A keeper, also known as a shunt, is a piece of iron that is temporarily added between the north and south poles of a magnet to prevent it from demagnetising during storage.


Magnetic pull

 Pull force of a pull magnetic sweeper 

The magnetic pull of a magnet is the maximum weight of ferromagnetic material it can hold.


Maximum operating temperature

 Very hot thermometer 

The maximum operating temperature refers to the maximum temperature the magnet may be continuously subjected to without significant loss of its magnetic strength.


The maximum operating temperature of a magnet can usually be found in the product specification and should be available for every variety of magnet.


Permanent magnet

 Red pocket horseshoe magnet 

A permanent magnet is one which emits a magnetic field without the need for any electricity, unlike electromagnets. In other words these magnets cannot be "turned off".


Rare earth magnets

 Rare earth elements in a periodic table 

Neodymium and samarium cobalt magnets are rare earth magnets. The name refers to their main component's position in the periodic table, rather than any rarity they may have.



 Sintered magnet 

Sintering is the term used to describe a metal compound which is heated without melting it into a liquid. This is an important stage of the manufacturing process of magnets.

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