Experiments: Magnetism

Magic Paperclip

Materials you need are:
one magnet
one paperclip
a length of cotton thread
sticky tape

Tie one end of the cotton thread to the paper clip and the other end must be sticky to a bench. Hold the magnet above the paperclip so that the paperclip is suspended in the air. It makes a good magic trick if you can hide the magnet in your hand.

Paperclip Diagram

Make a Floating Compass

Safety Rules:
Parent supervision
Take care with a knife and the needle

Materials you need are:
a sewing needle
a small bar magnet or a strong refrigerator magnet
a cork
a container of water
a sharp knife

First cut a thin slice of cork, and fill a container of water. Float the slice of cork on the water. Now make the magnetic compass by stroking the sewing needle from the eye to the point and lift, again from the eye to the point and so on. To test your compass, carefully rest it on the cork and observe it lining up in a north-south direction.

Make an Electromagnet

Safety rules:
Parent supervision
Take care with electricity

Materials you need are:
one torch battery (preferably 9 volts)
one long copper wire (about 1 metre long)
one long shiny iron nail
lots of paperclips

A coil of wire wrapped many times around an iron nail and connected to a power source (the battery) becomes an electromagnet. The more turns of wire, the stronger will be your electromagnet. Make about 40 tight turns of wire around the nail and connect it as in the diagram. Test your electromagnet by picking up paperclips.

Erase an Audiotape

Materials you need are:
a cassette recorder
an old audiotape
a magnet (e.g. a refrigerator magnet)

Record your voice or other sounds on an old audiotape. Remove the tape from the recorder. Bring the magnet up to the section of the tape that is showing and run it along the tape. Now play the tape again.

Some of your recorded sounds will have been erased. This is because the tape is magnetic and has been demagnetised by the magnet.