DISCOVER

# How to Reverse the Poles on a Magnet

Updated April 17, 2017

The process involved in reversing the poles of a magnet depends upon whether the magnet is an electromagnet or a permanent magnet. An electromagnet is a temporary magnet powered by electricity. Wire is coiled around an iron core. The ends of the wire are connected to a battery, producing an electric current that magnetises the metal core. A permanent magnet is a substance that is able to generate its own, lasting, magnetic field. The process of internally reversing the magnetic poles of a magnet is easier to do with an electromagnet than it is to do with a permanent magnet.

Turn off the power supply you are using to run your electromagnet.

Disconnect the wire lead from the negative terminal connector on your power supply. Disconnect the wire lead from the positive terminal connector on your power supply.

Reconnect the wire lead you disconnected from the negative terminal connector to the positive terminal connector. Reconnect the remaining wire lead that you disconnected from the positive terminal connector to the negative terminal connector. This will reverse the polarity of the battery and change the direction of the electric current. By changing the direction of the current, you reverse the poles of the electromagnet.

Activate the electric current by turning on the power supply.

Coil an insulated copper wire tightly around the permanent magnet. Wrap the coil in the direction of the magnet's polarisation. Leave at least 6 inches of wire free at each end.

Connect the ends of the wire to the terminals of a DC power supply, arranging the connection so that current flows in the opposite north / south direction of the permanent magnet's magnetic field.

Activate the electric current by turning on the power supply.

#### Tip

The easiest way to reverse the poles of a permanent magnet is to simply physically turn the magnet around 180 degrees. Depending upon the coercivity (magnetic intensity needed to demagnetise a magnet) of the material that makes up the permanent magnet, internally reversing the magnetic field may require a considerable amount of energy. You can use Faraday's law to calculate the amount of voltage needed and the length of time you need to run the electric current to invert the magnetic field of your permanent magnet.

#### Things You'll Need

• DC power supply
• Insulated copper wire