Making magnets
Have you used a magnet in school? If you have, the chances are it was a thick metal strip a few centimetres long. This kind of magnet is called a bar magnet. When you used your bar magnet you may have discovered what materials it could pick up or you may have put it on the side of your chair to see if it would grip a leg. If you had made a paper holder for your magnet, then hung the holder from a thread, you may have been surprised at what you found.

When a bar magnet is held from a thread so that it is horizontal it turns in a special way. One end turns and points towards the north. The other end points towards the south. If you move the magnet around in the classroom or change threads and paper holders it is always the same ? one end seeks the north and the other end seeks the south. The end which seeks the north, is said to have the north-seeking pole. The end that seeks the south is said to have the south-seeking pole. To make talking about the ends of the magnet easier, the end with the north-seeking pole is usually called the north pole and the end with the south-seeking pole is usually called the south pole.

If you were to cut a bar magnet in half, you would not get a piece of metal that was all north pole and a piece of metal that was all south pole. You would get two new magnets ?each with a north pole and a south pole. This may seem strange until you think about the way a magnet is made. If you were to cut up the magnet into smaller and smaller pieces you would just get smaller and smaller magnets. The reason for this is that a magnet is made up from millions of tiny magnetic regions called domains. Each domain is like a magnet. It has a north and a south pole. In a magnet the domains line up in rows all with their north poles pointing to one end of the magnet and their south poles pointing to the other end of the magnet. The end where all the north poles of the domains are pointing is called the north pole of the magnet. The end where all the south poles of the domains are pointing is called the south pole of the magnet.

An unmagnetised piece of steel such as a nail also has domains. The difference between the domains in a nail and the domains in a magnet is that the domains in the nail are pointing in all directions. This means that the nail does not have a north or south pole. This can be changed however if you a have a magnet handy. You may place one pole of the magnet at one end of the nail then stroke the magnet along the nail to the other end. You must then remove the magnet from the nail and take the pole of the magnet back to the end where you started the stroke. You must then stroke the nail again and again, perhaps fifty or sixty times in this way. When you have finished you will find that the nail may pick up a paper clip. What has happened inside the nail to make this change?
With each stroke of the magnet, some domains in the nail have been turned so their north and south poles face the same ends of the magnet. It is rather like a teacher in assembly trying to get all the children to face the front. At first many of the children may be looking at their friends or out of the window. As the teacher calls the children to attention most will face the front but some may need their name calling out before they face the right way. As the magnet passes along the nail with each stroke more and more domains move and 'face the right way'. As more domains line up, the magnetic power of the nail increases. If the nail has become a strong enough magnet it will point north and south when it is hung from a thread.

Is there another way of making a magnet by stroking it?
Yes, there is. Hold the nail in the middle. Place the north pole of the magnet at the middle
of the nail and stroke it to the end of the nail. This will make some of the domains line up with their south poles towards the end of the nail. Now turn the nail round and turn the magnet round too. Bring the south pole of the magnet to the middle of the nail and stroke it to the end of the nail. This will make some of the domains line up with their north poles towards the end of the nail. Keep stroking each end of the nail as you began and after about fifty or sixty strokes you may find that the nail will pick up a paper clip.

Are there any ways of making a magnet without stroking it?
Yes. There are two simple ways to make a weak magnet. Firstly put a pin close to, but not touching, a string magnet. The pin and magnet should be lined up side by side. Leave the pin and magnet for a few days. Over this time the magnetic force from the magnet turns some of the domains in the pin and lines them up to give the pin a north and south pole. For the second way find out the direction of north and south using a compass. Take away the compass and line up a pin so that one end points north and the other points south. Leave for a few days. During this time the force of the Earth's magnetism will turn some of the domains in the pin so that it has a north pole and south pole.

How are strong magnets made?
They are made in a special factory. The metal bar to be made into magnet is placed in a coil of wire. A current of electricity is then passed through the coil. This turns the coil into a very strong magnet. Its power works on the domains in the metal bar and turns them, so all their north poles point to one end and all the south poles point to the other end.

Can a magnet lose its magnetism?
Yes, it can. If the domains stop pointing towards the ends of the magnet, the magnet loses its power. The domains can be turned if the magnet is heated or if it is beaten with a hammer. Even dropping the magnet shakes up the domains and makes the magnet weaker.

How can magnets be cared for?
It is important to keep all the domains lined up. The magnets must be kept away from strong heat because this will make the domains fall out of line. Also, and probably more importantly, you must take care not to drop magnets or bang them. This will shake up the domains too. If toys have a horseshoe magnet, you should put a small metal bar across the ends. This bar is called a keeper and helps the domains stay in place. The keeper does this by becoming a magnet itself while it is in contact with the magnet. Bar magnets should be arranged in pairs side by side. The north pole of one magnet should be placed next to the south pole of the other magnet. Keepers should be placed across both ends of the magnets to keep the domains lined up.