A magnet is a piece of rock or metal that can pull other metals towards it. The force of magnets is called magnetism. Together withgravity and electricity it is a basic force of nature. Early humans discovered magnets and magnetism thousands of years ago. They found out that certain types of rock, called loadstone, pulled iron and other metal objects towards it. After some time they found out that thin pieces of such a rock would always point in one direction if you hung it on a piece of thread . The ends of such a metal are the poles of a magnet. All magnets have a magnetic field around them, the force between the two poles.
Magnets attract or repel other metals. This is because every magnet has two poles: a north and a south pole. North and south polesattract each other but two north poles or two south poles push each other apart.
Our planet is also a big magnet with a North and a South Pole. But the Earth’s magnetic poles are not in the same place as the geographic poles. The magnetic North Pole, for example, is in northern Canada. Compasses always point to the magnetic poles, not to the geographic ones.
Magnetism comes from electrons , the tiny particles that fly around the nucleus of an atom. They are negatively charged and produce a very weak magnetic field. When many of these electrons point towards the same direction they can pull metals to them.
It is also possible to make a magnet by taking an existing one and rubbing another piece of metal with it. If you keep rubbing the new piece of metal in the same direction its electrons will start to point in that direction , thus creating a new magnet.
If a magnet keeps its magnetic field all the time we call it a permanent magnet. However , not all magnets are permanent . Some objects become magnets only when electricity passes through them. They are called electromagnets. There are many examples of such electromagnets in everyday life: car motors, railway signals, loudspeakers .
Magnetism and electricity
In the 1700s scientists discovered that magnetism and electricity had similar features. Just like magnets have two poles, electricityhas positive and negative charges . A positive and a negative charge attract each other and two negative or two positive charges repeleach other.
After they had found this out they started making useful tools and machines with the help of electricity and magnetism. The Danish physicist Oersted sent electricity through a wire and put a compass near it. To his surprise the compass needle moved. Soon after that the first electromagnet was made by making a wire into a coil and sending electricity through it.
