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Practicals

Oersted's Experiment
AKA: Electromagnetic Field

Summary

Electric current through a wire produces a magnetic field.

Operation

Hans Christian Oersted first demonstrated this famous principle in 1820. The demonstration became known as Oersted’s Experiment and continues to be conducted in schools today. It is a very simple but effective demonstration which demonstrates how an electromagnetic field can be created.

The demonstration involves connecting a length of plastic coated wire to a low voltage labpack. When a current is applied to the wire and a small compass brought near, the dial on the compass should move, proving the presence of an electromagnetic field.

Equipment required (per demo):

  • 100mm insulated copper wire (single core)
  • Low voltage labpack (1V at 10A or less)
  • Small plotting compass
  • Wire strippers

The wire required is single core and PVC coated. The same type as is used for making transformers. This should be stripped of a few centimetres of insulation at each end and then connected to the DC terminals of the low voltage labpack.

The power should only be switched on for a very short time, otherwise the wire will get hot and the labpack thermal fuse may trip. Ideally the equipment should be placed on a heatproof mat just in case the wire gets too hot.

Safety

 CautionThe contents of this page are for information only. Please refer to CLEAPSS, SSERC or ASE safety advice and/or publications before undertaking any preparation, practical experiment or using any equipment featured on this site or any other.