‘All about Magnetism’
‘All about Magnetism’ by Leon Gray
1. No one really knows what causes magnetism. Scientists think that the movement of tiny particles called electrons inside atoms causes magnetism. These same particles create electricity. Electricity and magnetism are closely related.
2. In an atom, electrons spin around the nucleus in pairs, but in opposite directions — — one up and one down. It is the up-and-down spinning movement of electrons that causes magnetism.
In naturally magnetic materials such as iron and nickel, the atoms contain unpaired electrons. This creates a magnetic moment, which gives the material its magnetic effect.
3. Some metals, such as cobalt, iron and nickel, are permanent magnets. Many metal alloys are also permanent magnets. Steel is a magnetic material. This alloy is made from iron, carbon and other metals such as chromium, nickel and tungsten.
4. Every magnet has a magnetic field around it. This is the space around a magnet in which the magnet can attract other magnetic materials. If the material is outside this invisible force field, the magnet cannot attract it.
5. Earth’s magnetic field may be very weak, but it stops damaging solar particles from the Sun hitting the Earth. When these solar particles hit the magnetic field around the planet (magnetosphere), especially around Earth’s North and South poles, they create colourful light displays in the sky called auroras.
6. There are two main ways to demagnetize a magnet. The most common method is to align the magnet in a magnetic field that is aligned in the opposite direction to the magnet. Another way is to heat the magnet above a certain critical temperature. Heat makes the domains drop out of alignment.
7. Scientists use the tesla (T) to measure the strength of a magnetic field. They use a unit called the gauss (G) to measure smaller magnetic fields. One tesla is equal to 10000 gauss.
Earth’s magnetic field measures about 0.5 gauss at the surface of the planet. Fridge magnets measure 100 gauss, while a strong electromagnet can measure 1500 gauss.
8. Michael Faraday moved a magnet near a wire and found that electricity flowed through it. The magnetic field cutting through the wire had created an electrical current through the wire. Today, most of the electricity in the world is made in this way.
9. Computers use electromagnets to store information. A computer processes information as pulses of electricity. A pulse of electricity is stored as a ‘1’ and no pulse is stored as a ‘0’.
10. Scientists are developing small magnets that are only the size of atoms called ‘nanomagnets’. They are used to make extremely small machines, or ‘nanomachines’. One of the main uses is in medicine. Doctors hope to use nanomachines to treat cancer and other diseases.
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