AIM OF THE EXPERIMENT: To show that an electric current creates a magnetic field.MATERIALS: a metre of insulated wire up to 1 mm thick, a long iron nail, a 6-volt battery, metal paper clips, an adult helper. METHOD: Wind the wire tightly round the nail, leaving about 15 cm of free wire at each end.
Ask your helper to scrape the insulation off both ends of the wire.
Fasten one end of the wire to one terminal of the battery.
Holding the free end of the wire against the other terminal, touch the heap of paper clips with the nail.
Lift the nail without taking the ends of the wire off the terminals of the battery.
When the nail starts to get warm, disconnect the wire from the battery.
RESULTS: The paper clips stick to the nail.
WHY? There is a magnetic field around every wire that carries an electric current. Around a straight wire the magnetic field is very weak. In this experiment it was made stronger by winding the wire round the nail and passing the current from the battery through the wire. The iron nail became magnetised and drew the paper clips to it.