What is magnetism used for?
Do you have fridge magnets? Have you ever noticed that the refrigerator door pulls itself shut when you start to close it? These magnets are exactly like the bar magnets described in Introducing magnetism. They have two poles, one on each side – the distance between them is just much thinner. The attractive properties of magnets are commonly used and magnetism is also utilised in a variety of ways in our everyday lives.
Magnetism and electricity are forces generated by the movement of electrons. They are both electromagnetic forces, and the interplay of these two forces is the basis for many modern technologies. Electromagnets are magnets that are generated by electric fields. They have the advantage over regular magnets in that they can be switched on and off. Try making your own electromagnet. Many modern technologies employ electromagnetics and utilise magnetic fields, for example, MRI and superconductors.
Magnets are essential components in motors. The electrical current travelling through a coil of wire creates an electric field that can be influenced by a magnetic field. The interplay of the two fields causes movement. This movement, if channelled in the right direction and attached to other moving parts, can be used as a motor. Try making your own simple electric motor.
Magnets are also used in electricity generation. Most electricity generation in New Zealand is renewable. Power stations use wind, water and geothermal energy (using steam) to turn large turbines. The turbines are attached to huge generators that use electromagnets to transform kinetic energy to electrical energy. When the large turbines spin, the copper coils rotate within magnets causing the electrons in the wire to move in one direction and generating electricity.
There are several articles and a PLD session related to magnetism. They include Introducing magnetism, Mapping the Milky Way’s magnetic field, Fossil compasses, Magnetic resonance imaging (MRI) and Exploring magnetism.