Magnets

Page 1

Magnets produce magnetic fields

All magnets have two poles - north and south.

A magnetic field is a region where magnetic materials e.g. iron experience a force

Magnetic field lines or lines of force are used to show the size and direction of magnetic fields. They always point from north to south.

Placing the north and south poles of two permanent bar magnets near each other creates a uniform field between the two magnets.

Experiment to see the magnetic field patterns:

You can use compasses and iron fillings to look at magnetic field patterns

They align themselves with magnetic fields

You can use multiple compasses to se the magnetic field lines coming out of a bar magnet or between two bar magnets

You could also use iron fillings to see magnetic field patterns. Just put the magnet under a piece of paper and scatter the iron fillings on top.

If you don't have lots of compasses, you can just use one and move it around.

Magnetism can be Induced

Magnets affect magnetic materials and other magnets.

Like poles repel each other and opposite poles attract

Both poles attract magnetic materials that aren't magnets

When a magnet is brought near a magnetic material then that material acts as a magnet

This magnetism has been induced by the original magnet

The closer the magnet and the magnetic material get, the stronger the induced magnetism will be.

Page 2

Electromagnetism

When an electric current flows it produces a magnetic field

The larger the current the stronger the magnetic field

The direction of the magnetic field depends on the direction of the current

Magnetic field around a straight wire

There is a magnetic field around a straight, current-carrying wire

The field is made up of concentric circles with the wire in the centre