Resource 3: Background to magnetism
Teacher resource for planning or adapting to use with pupils
Magnets, magnetic materials and non-magnetic materials
Questions for students to predict the answers to before they test their predictions
Will a magnet pick up all the materials?
What do all the magnetic materials have in common?
Will the magnet attract or pick up a piece of aluminium?
Will the magnet attract or pick up a piece of iron?
How can you tell the difference between a magnet and a magnetic material?
Additional question and what you need to answer it
How can you find the north pole of a magnet?
In order to find the north pole of a magnet, you must either
- have another magnet with the north pole marked on it (and which you know is correct – see below) or
- know which way is north.
You need a piece of string to suspend your magnet.
What you will need for each group to sort the samples
- At least one bar magnet for testing the samples.
- At least one other magnet to be a sample. This could be another bar magnet, but there are other magnets you could use, too: a ring magnet from an old or broken loudspeaker, a magnet from an old motor, a fridge magnet, a magnet from a magnetic door lock, a small magnet used for earrings or jewellery fasteners or from some handbag closures.
- Small samples of non-metallic materials, e.g. a piece of wood, a piece of cardboard, a piece of plastic.
- Small samples of metallic materials or objects made of metal: try to get a range of metals, e.g. piece of copper sheet or copper pipe, piece of aluminium/aluminium foil/empty aluminium drink can, piece of steel/empty steel food can/steel paper clips, iron nails.
- Two trays.
Before the lesson, put all the samples for a group on a table, spread them out as much as possible and mix them up. (If you have several magnets, make sure they don’t attract other items on the table!)
Sorting the samples
One person in the group should hold one end of the ‘tester’ bar magnet above each sample in turn (but don’t touch the samples with the magnet). They should decide whether the sample is attracted or repelled or neither of these.
Someone else in the group should remove all the items that are not attracted to the magnet or repelled by it and put them on a tray. (This should have all the non-magnetic materials.)
The student who has the magnet should turn the magnet round to use the other end and hold the end of the magnet over each of the samples left on the table.
Someone else should remove any samples that are not repelled by the magnet, and put them on another tray. (This should have all the magnetic materials on it. The only objects left on the table should be the magnets.)