In 1819 a Danish scientist named Hans Christian Oersted discovered a close relationship between electricity and magnetism with this experiment. The new knowledge led to the study of electromagnetism.
Materials you will need:
- Energizer® Power Pack
- Switch or alternate commercial knife blade switch
- Cork – ¼” slice off large end of ¾” cork
- Small non-metallic bowl
- No. 22 insulated copper wire
- One horseshoe or bar magnet
- One needle
- Modeling clay
- 1. Rub from the middle to the pointed end of the needle along one side of the magnet. Make sure to rub in the same direction 30-40 times to magnetize the tip of the needle. Test the needle magnetization by trying to pick up another needle. If you can pick up the second needle you are ready to put your compass together.
- 2. Fill the bowl with water. Tape the needle on the cork and place the cork in the bowl.
- 3. Move the magnet around the bowl and observe how the needle reacts to the magnet.
- 4. Place a wire on top of the dish and secure it with clay as illustrated. Connect one end of the wire to the switch and the other to the (+) of the “Power Pack”. Connect another wire from the switch to the negative (-) of the “Power Pack”.
- 5. Close the switch momentarily and observe how the needle moves then re-open the switch. Do not leave the switch on for extended periods. There is low resistance in the circuit and the batteries will heat up if the circuit is closed for more than a few seconds at a time.
When the switch is closed the current flowing through the circuit creates a magnetic field around the wire. The magnetic needle reacts to the magnetic field in the circuit and turns perpendicular to the wire. This experiment is one of the most important in the utilization of electric power as it led to the discovery of electromagnetism and the development of the electric motor.