Theory of Magnetism

If a magnetic piece of steel rod is cut into smaller pieces, each piece is a magnet with a N or a S pole.

Therefore a magnet can be said to be made of lots of "tiny" magnets all lined up with their N poles pointing in the same direction. At the ends, the "free" poles of the "tiny" magnets repel each other and fan out so the poles of the magnet are round the ends.

 

Magnetised Bar Unmagnetised

 

In an unmagnetised bar the "tiny" magnets point in all directions - the N pole of one neutralized by S pole of another. Their magnetic effects cancel out and there are no "free poles near the ends.

 

This theory explains:

Destroying magnetism

This can be done by:

Contents

History of magnetism, What is a magnet
What do magnets do, Test for a magnet
Magnetic fields
The Earth's magnetic field
Induced magnetism
Magnetic properties of iron and steel
Storing magnets
Making a magnet
Electro-magnets
Primary science applications
Fleming's Left Hand Rule
Self assessment
Comments, reflections and study action plan