Physics

4.2 - Permanent & Induced Magnets

6 min

Magnetic materials

Permanent and induced magnets

Soft and hard materials

note 1 of 2

Permanent and induced magnets

A permanent magnet produces its own magnetic field all the time (e.g. a bar magnet).
An induced magnet is a magnetic material that becomes a magnet only when placed in a magnetic field.

The force is always attractive

The force between a permanent magnet and an induced magnet is always attractive.
A pole on a permanent magnet induces the opposite pole in the nearest part of the magnetic material:
- A north pole induces a south pole.
- A south pole induces a north pole.
The closer the magnet is to the material, the stronger the induced magnetism.

A bar magnet labelled permanent magnet, a plain grey bar labelled magnetic material, then an arrow to the pair side by side with the grey bar now marked N and S, labelled induced magnet.

note 2 of 2

Soft and hard magnetic materials

When removed from a magnetic field, an induced magnet loses its magnetism.
Magnetically soft materials (e.g. pure iron) are easily magnetised and lose their magnetism very quickly.
Magnetically hard materials (e.g. steel) are harder to magnetise but keep their magnetism. Permanent magnets are made from magnetically hard materials.

key terms

TermDefinition

Permanent magnetA magnet that produces its own magnetic field all the time.

Induced magnetA magnetic material that becomes a magnet only when placed in a magnetic field.

Magnetically softDescribes a material that is easily magnetised and loses its induced magnetism very quickly.

Magnetically hardDescribes a material that is harder to magnetise but keeps its induced magnetism.

end of notes

Key points to remember

Permanent and induced magnets

A permanent magnet produces its own magnetic field all the time (e.g. a bar magnet).

An induced magnet is a magnetic material that becomes a magnet only when placed in a magnetic field.

The force is always attractive

The force between a permanent magnet and an induced magnet is always attractive.

A pole on a permanent magnet induces the opposite pole in the nearest part of the magnetic material:

A north pole induces a south pole.
A south pole induces a north pole.

The closer the magnet is to the material, the stronger the induced magnetism.

Soft and hard magnetic materials

When removed from a magnetic field, an induced magnet loses its magnetism.

Magnetically soft materials (e.g. pure iron) are easily magnetised and lose their magnetism very quickly.

Magnetically hard materials (e.g. steel) are harder to magnetise but keep their magnetism. Permanent magnets are made from magnetically hard materials.