Magnetic fields

The region around a magnet where a force acts on another magnet or on a magnetic material (iron, steel, cobalt and nickel) is called the magnetic field.

The force between a magnet and a magnetic material is always one of attraction.

The strength of the magnetic field depends on the distance from the magnet. The field is strongest at the poles of the magnet.

The direction of the magnetic field at any point is given by the direction of the force that would act on another north pole placed at that point. The direction of a magnetic field line is from the north (seeking) pole of a magnet to the south(seeking) pole of the magnet.

A magnetic compass contains a small bar magnet. The Earth has a magnetic field. The compass needle points in the direction of the Earth’s magnetic field.

Students should be able to:

• describe how to plot the magnetic field pattern of a magnet using a compass
• draw the magnetic field pattern of a bar magnet showing how strength and direction change from one point to another
• explain how the behaviour of a magnetic compass is related to evidence that the core of the Earth must be magnetic.

WS 2.2