Magnets have magnetic fields — Physics, 11–13
A magnet can affect some objects without touching them because the space around it contains a magnetic field.
An invisible magnetic field
A magnet changes what happens in the space around it. This region is called its magnetic field, and it can attract or repel another magnet without contact. The field is strongest near the poles, usually called north and south.
Why study something invisible?
A simple push or pull does not explain how a magnet acts across a gap. The field idea gives us a way to describe and predict that action, even when we cannot see the field itself. Iron filings or a compass reveal its pattern indirectly.
Mapping a bar magnet
Place a bar magnet under a sheet of paper. Put a small compass at one point, mark the direction of its needle, and move it a short distance along that direction. Repeat the marks around the magnet. The curved paths show the field’s direction, and the closer marks near the ends show where it is stronger.
Not every metal is magnetic
It is reasonable to expect a magnet to attract every metal, because iron objects are common and many look alike. But ordinary magnets strongly attract materials such as iron and steel, not copper, aluminium or gold. The word “metal” describes a large family, not one magnetic behaviour.
Navigation and machines
Compasses use Earth’s magnetic field to give a direction, which helps ships and hikers navigate. Magnetic fields also let speakers turn electrical signals into moving sound-making parts. In scrapyards, powerful electromagnets lift iron and steel, then release them when the current is switched off.
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