1. Magnetic and Non-Magnetic Materials

Magnetic materials

Some materials are affected by magnets. These are called magnetic materials.

Examples:

  • Iron
  • Steel
  • Nickel
  • Cobalt

Properties:

  • They are attracted to magnets
  • They can be magnetised

Non-magnetic materials

Most materials are not affected by magnets.

Examples:

  • Wood
  • Plastic
  • Aluminium
  • Copper
  • Glass

Properties:

  • They are not attracted to magnets
  • They cannot be magnetised

Only certain materials have the correct internal structure to show magnetism.

2. Why Magnets Have Magnetism (Domain Model)

Electrons and magnetism

Magnetism comes from electrons inside atoms.

  • Electrons are moving electric charges
  • A moving electric charge creates a magnetic field
  • Each electron therefore produces a tiny magnetic field

In many atoms, the magnetic fields from electrons cancel out.
In some materials (like iron), they do not cancel completely.

Magnetic domains

In magnetic materials:

  • Groups of atoms form regions called magnetic domains
  • Inside each domain, the magnetic fields from electrons are aligned
  • Each domain acts like a tiny bar magnet

Why most objects are not magnets

In an unmagnetised magnetic material:

  • Domains point in different directions
  • Their magnetic fields cancel out
  • The object has no overall magnetism

This is why a piece of iron is usually not a magnet.

How a permanent magnet gets its magnetism

When a magnetic material is magnetised:

  • Many domains line up in the same direction
  • Their magnetic fields add together
  • The object develops a net magnetic field

If the domains stay aligned, the object becomes a permanent magnet.

3. Induced Magnets

What is an induced magnet?

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

How induced magnetism happens

When a magnetic material is placed near a magnet:

  • The magnetic field causes domains to realign
  • The object becomes temporarily magnetised

When the magnet is removed:

  • The domains return to a more random arrangement
  • The magnetism disappears

Properties of induced magnets

  • Always attracted to a magnet
  • Magnetism is temporary
  • Common in soft iron

Example:

  • An iron nail sticks to a magnet but falls off when the magnet is removed.

4. Magnetically ‘Soft’ and Magnetically ‘Hard’ Materials

Magnetically soft materials

Magnetically soft materials are:

  • Easy to magnetise
  • Easy to demagnetise

What happens inside:

  • Domains move and realign easily
  • Domains do not stay aligned for long

Example:

  • Soft iron

Uses:

  • Electromagnets
  • Transformer cores

These materials are useful where magnetism needs to switch on and off.

Magnetically hard materials

Magnetically hard materials are:

  • Difficult to magnetise
  • Difficult to demagnetise

What happens inside:

  • Domains are harder to move
  • Once aligned, domains stay aligned

Example:

  • Steel

Uses:

  • Permanent magnets
  • Compass needles

These materials are used where magnetism needs to be permanent.

5. Overall Summary

  • Only some materials are magnetic
  • Magnetism comes from moving electrons
  • Magnetic domains explain why materials can be magnetised
  • Permanent magnets have aligned domains that stay aligned
  • Induced magnets are temporary
  • Soft magnetic materials lose magnetism easily
  • Hard magnetic materials keep magnetism