Magnetism is an invisible force that attracts (draws towards itself) or repels (pushes away) certain materials. Any object that can attract or repel magnetic materials is classed as a magnet. The area around a magnet that is influenced by its magnetism is referred to as its magnetic field. It is strongest at the “poles” (usually the ends) of the magnet. Opposite magnetic poles will attract each other, while like magnetic poles repel each other. Planet Earth has
MAGNETISMits own magnetic field, driven by the molten material that circulates beneath the surface.The two silver ends of a horseshoe magnet are the north and south pole108
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MAGNETIC MATERIALS
When an unmagnetized magnetic material is placed in a magnetic field it becomes a magnet itself, either temporarily or permanently. Materials such as nickel and iron are easily magnetized and demagnetized and are known as soft magnets. Alloys (mixtures) of iron, nickel, and aluminium are difficult to demagnetize and are referred to as hard, or permanent magnets.^2ATTRACTION
Iron filings sprinkled around a magnet will reveal the magnetic force field in action. If you bring two magnets together so that a north pole is facing a south pole, then the filings will bridge the gap, showing attraction.^3REPULSION
If you bring two magnets together with their two north poles or two south poles facing, you can feel the pushing force between them as their magnetic fields come into contact and the like poles repel each other.^4MAGNETIC STRENGTH
The strength of the attraction that holds all these objects together can also be used in industry. Large cranes with a lifting magnet are used to move tonnes of scrap metals and old cars, as well as to load heavy machine parts.The magnetic north pole is in northern Canada, about 1,600 km (1,000 miles) from the geographic North PoleNear this magnet the scissors are temporarily magnetic so there is attraction417108_109_Magnetism.indd 108 03/01/19 12:10 PM