Magnets are objects, which have an invisible force. This force causes them either to repel or attract other objects. Magnets have two poles which causes these forces, a North pole and a South pole. Like poles repel and unlike attract. Iron and Nickel are the most common magnetic materials.

Today Magnets are used in everyday appliances around the home e.g.: hairdryers, telephones, vacuum cleaners, electric mowers, cassette recorders. Even the computer you are using now uses magnets to store information on it. Trains make use of magnets as well. By using large electromagnets trains moves along without touching the rails. This is possible because the magnets in the train and those in the rail repel each other. The Earth also acts like a giant magnet, using a compass one can find a bearing for North.

Cutting a magnet in half creates two separate magnets which both have a North Pole and South Pole. Scientists in general believe that is not possible to create a magnet with only one pole (although some think a few of these one pole magnets may have been left over from the Big Bang, the huge explosion which created our Universe).

Magnetic Fields

A magnet is surrounded by an invisible force field. It is possible to see how this field behaves by simply placing a sheet of paper above a magnet and sprinkling some iron fillings around the magnet.

The magnetic force is at its strongest around the poles and gets progressively weaker as you move further away. This can be seen by how the iron fillings are scattered on the paper.

Electromagentism

This is the idea that magnetism can travel from one object to another even though they are insulated. An example of how magnetic induction is used is in transformers.

Two coils of wire are wrapped around an iron core. The primary coils are connected to the power supply while the secondary coils are connected to the device.

An electromagnetic field is created from the primary coils and this induces a magnetic field in the core. This in turn induces a current in the secondary coil.

The number of coils is proportional to the amount of voltage, so a transformer is used to increase or decrease the voltage.

  secondary voltage       secondary turns
    primary voltage     =     primary turns

Some Experiments to Try

EXPERIMENT 1: With a magnet, a paperclip, a piece of tape and a ware you can make a kite of ironwire. Attach one end of the wire to the underside of the paperclip and the other end with the tape to a table. Lift up the paperclip with the magnet. You can hold the magnet in a way that there is some space between the magnet and the paperclip, or hold a piece of paper between the magnet and the paperclip, without letting the paperclip fall.

EXPERIMENT 2: You can make a compass yourself, by rubbing 20 times with the south pole of a magnet in the length over the eye of a needle. Fasten a long small thread to the middle of a needle and the needle will point to the north.

EXPERIMENT 3: With balls out of a ball-bearing you can do an experiment too. Hang the balls one by one on the magnet. The magnetic field of the magnet penetrates each ball and makes that ball magnetic. If you have done experiment 1, you know that the magnetic field continually becomes weaker if you go further of the magnet. Through that is it that only a few balls can hang on the magnet. You can try to take the uppermost ball and the magnet and move up the magnet slowly. After a while some balls will fall, because the magnetic field is too weak there to attract the balls.