Stroke a steel needle with a magnet and it stays magnetic for years. Do the same to an iron nail and it loses it almost at once. That difference decides which metal belongs in a fridge magnet and which in an electromagnet.
Magnetically soft materials such as iron magnetise and demagnetise easily, ideal for electromagnet cores. Magnetically hard materials such as steel keep their magnetism, ideal for permanent magnets. The magnetic materials are iron, steel, cobalt and nickel.
A magnetically soft material (such as iron) magnetises and loses its magnetism easily; a magnetically hard material (such as steel) keeps its magnetism. Induced magnetism is when a magnetic material becomes a magnet while in a magnetic field.
Magnetic materials are iron, steel, cobalt and nickel.
Compare how soft iron and hard steel hold or lose their magnetism.
Four quick checks. Each correct answer earns XP and lights this skill on your star map.
A permanent magnet is best made from...
The core of an electromagnet is best made from...
A magnetically soft material...
Which list contains only magnetic materials?
Soft for cores that switch on and off, hard for magnets that must stay magnetised.
| Soft (iron) | Hard (steel) |
|---|---|
| Magnetises very easily | Harder to magnetise |
| Loses magnetism easily | Keeps its magnetism |
| Used for electromagnet cores | Used for permanent magnets |
| Good temporary magnet | Good permanent magnet |
Magnetically soft does not mean physically soft. It means easy to magnetise and demagnetise, like iron. Steel keeps its magnetism, which makes it a good permanent magnet but a poor electromagnet core.
Unlocks once the four checks above are done. Worth more XP, written in the style of Paper 2.
An electromagnet must switch its magnetism on and off quickly. Its core should be...
A fridge magnet needs to stay magnetic for years. It is made of a magnetically...
An unmagnetised iron nail is held near a strong magnet and picks up paperclips. This is an example of...
Soft and hard magnetic materials are mapped. Keep the chain going.