The homopolar motor is one of the simplest electric motors. They use electromagnetism to support motion and were developed by Michael Faraday in the 1800’s. Homopolar force can be explained using the Lorentz force. This force is caused by electric currents and magnetic fields that are perpendicular to each other, causing rotation.

In one of our past blogs, we showed you how to make a similar homopolar motor. The one we are designing today uses two magnets to create forward propelling motion instead of spinning. This motor will act like a small car, moving forward when placed properly. To get started with your DIY magnet car, you’ll need some supplies you can probably find in your kitchen, along with some magnets, of course!

Supplies

  • 2 Double A Batteries
  • Aluminum Tin Foil
  • 4 Neodymium Rare Earth Disc Magnets (2 different sizes)

Directions

  1. Lay out the tin foil on a flat table. You can use as much or as little as you desire, but it will affect how far the battery will roll.
  2. Attach the neodymium magnets on each side of the AA battery.
  3. Place the battery and magnets directly onto the tin foil and watch as they roll away from you.
  4. If you have two different sized magnets, place one on each side of the battery and place it onto the tin foil. What happens, and why do you think it does?
  5. Repeat step 4 with two separate batteries, setting them in the exact spot seconds apart. Does the second battery catch the first?

When an electrified conductor is placed in a magnetic field that runs perpendicular to it, it creates torque and propels the conductor. In this case, the aluminum foil is the conductor and the resulting torque drives the magnets and battery forward because of their rounded design.

After you complete your magnet battery cars with AA batteries, try using different sized batteries and race them against each other. Let us know in the comments section below which combination of battery and magnet sizes go the fastest and or work the best. To get a better visual of how the cars work, watch the video below made by Youtube user Magnetic Games.