Make Your Own Homopolar Motor

You can create your own simple motor with three common materials. But your design doesn't have to be simple; get creative and make your homopolar motor unique!

What You Need

  • Copper Wire
  • A neodymium magnet
  • A AA battery

What to Do

Homopolar Motor Forces

The current flows downward in both wires, and the magnetic field is pointing approximately outward when it reaches the wires on the side. Consequently, by the right hand rule, the force points "into the page" on the left side and "out of the page" on the right side, causing the wire to rotate around the battery.

1. Attach the magnet to the negative side of the battery.

2. If the copper wire is coated, ask for supervision as you or a guardian strip the wire.

3. Bend the wire so that one end touches the positive battery terminal and the other touches the magnet under the negative battery terminal. You'll need copper wire to bend around two sides of the battery; for example, the heart shape seen in the video above works well.

4. As the copper wire grazes the magnet the wire will begin to spin.

What's Going On?

The copper wire connects the positive battery terminal to the magnet at the negative battery terminal, completing the circuit. Consequently, a current of electrons will flow through the wire.

Due to the close proximity of the magnet at the bottom of the battery, this current actually flows in the presence of a magnetic field. When current flows in a magnetic field, it'll experience a force — the Lorentz force — that acts perpendicular to both the current's direction and the direction of the magnetic field.

This force causes the wire to spin in a circle as you can seen in the video at the top of the page.

Apply It!

Try bending the wire in different shapes to make the copper wire spin. Make sure one end is touching the positive terminal and the other is touching the neodymium magnet.

-Jamie Garrett