Magnetic fields

The field idea

Wrong Track: The magnetic field is those iron filings around it.

Right Lines: The magnetic field is the space around the magnet where it will attract or repel other magnets.

Fields cannot be seen

Thinking about the learning

The very idea of a magnetic field is a demanding one to get hold of. The fact of the matter is that the magnetic field is a theoretical idea invented by physicists to allow us to describe the action of magnets as they attract and repel. It is possible to maintain that it is not anything real, there is nothing to see or touch around the magnet. When pupils first come across this idea of the magnetic field, it is not surprising that they sometimes go off down the wrong track in their thinking!

Thinking about the teaching

It is important to keep coming back to the essential idea that the magnetic field is the space around the magnet where it exerts a force. You might explore that space with iron filings and plotting compasses, but these simply tell us about the direction and strength of the force acting, they do not make the field any more real.

If you look in a science textbook at a magnetic field diagram for a bar magnet it will almost certainly show a 2D representation. It is worth emphasising however, that the magnetic field exists in the space all around the magnet – magnetic fields exist in 3D spaces.

Teacher Tip: Ask the pupils!

You might introduce the idea of magnetic fields, carefully making all of the key points set out above, but even then it is worth asking your pupils what they understand by the idea of magnetic field. Ask them to jot down a sentence or two. You might be surprised by what they write!