The National MagLab is funded by the National Science Foundation and the State of Florida.

# Ørsted's Compass

In 1820, Hans Christian Ørsted discovered the relationship between electricity and magnetism in this very simple experiment.

In 1820, Hans Christian Ørsted stumbled upon a discovery that birthed the study of electromagnetism. While setting up materials for a lecture, Ørsted happened to bring a compass close to a live electrical wire. He noticed that the needle of the compass jumped when close to the wire. After more experimentation and documentation, he officially proved that magnetic fields are created when current travels through a wire, thus proving that electricity and magnetism are connected.

Play with the tutorial below to experience the phenomenon as Ørsted did.

## Instructions

1. Identify all the parts of Ørsted’s setup and take note of the direction the compass needle is pointing.
2. Close the circuit by pushing the “on” button.
3. Observe what happens to the compass needle when electricity is flowing through the wire.
4. Flip the battery, and watch the compass needed change direction.
5. Turn the system off. Watch the needle move back to pointing North when there is no longer current running through the wire.

The battery Ørsted used was a voltaic pile, which is made of copper and zinc plates in an acid solution. A metal wire is connected to the battery and held up by wooden clamps. A compass is placed below the wire. The compass needle points north until the circuit is connected because it is reacting to the earth’s magnetic field. When the system is turned on, the magnetic field of the wire overpowers the force of the earth’s magnetic field on the needle. When the battery is flipped, the direction of the current is reversed and so is the way the needle is pointing.