This video that we saw on The Kid Should See This prompted me to buy the supplies to try this at home with my son:
Supply List for Homopolar Motor
I bought the wrong magnets so I would suggest you buy this smaller one instead. It’s less expensive too!
Neodymium Magnet, $10
Be careful with these magnets. Make sure no one puts them in their mouth. Swallowing neo magnets is dangerous. Also, do not put it near cell phones or computers. These are very strong magnets!
4 Yards of Copper Wire, $3.50
Wire Cutters, $4.37
You could use scissors instead.
AA Battery, $6
You just need one AA, C, or D-cell battery. The D-cell battery fits the best on the Neodymium battery that I specified but the AA battery worked fine too. I would just use whatever you have handy.
(Note that you can use the magnets, wire cutters, and copper wire for more experiments like this homopolar race car, homopolar tiny dancers, or a simple electric toy train.)
After we had our supplies, we watched a background video on how the homopolar motor works from a UCLA professor. I was hoping to understand the physics behind this science project. The professor also built the homopolar motor and it looks so easy!
Background Video from UCLA Professor on Homopolar Motor
A homopolar motor is a direct current electric motor with two magnetic poles, the conductors of which always cut unidirectional lines of magnetic flux by rotating a conductor around a fixed axis so that the conductor is at right angles to a static magnetic field. from Wikipedia
A homopolar motor creates rotational movement because of what is known as the Lorentz force. What’s happening is that electrical current is flowing from the positive terminal of the battery to the negative and into the magnet. From First 4 Magnets
Lorentz Force: the force that is exerted by a magnetic field on a moving electric charge.
So, we are still a little mystified by the physics behind the homopolar motor but the setup seems to create a magnetic field that sends forces out and then down, thus causing the wire to spin. The Lorentz Force is new to us. We have enough information to get started.
Our first obstacle is the Neodymium Magnet. I accidentally bought the much bigger one-inch size ones that are very powerful. We discover spacers between the three magnets which, of course, means the current can’t pass through all three. It’s a struggle to remove the spacers and get just one. My fingers get smashed in the process; these magnets are strong!!
Next, my son creates the wireframes that go around the setup. No matter how carefully he builds them, he can’t seem to get them spinning. On a bright note, the battery which is on top of the Neodymium magnet is getting hot. There’s definitely energy being created and conducted but the darn thing won’t spin.
To examine any book or item more closely at Amazon, please click on image.
As an Amazon Associate, I earn from qualifying purchases.
Follow PragmaticMom’s board Science Fun on Pinterest.
Follow PragmaticMom’s board STEAM on Pinterest.
My books:
Amazon / Signed or Inscribed by Me
Amazon / Signed or Inscribed by Me
Food for the Future: Sustainable Farms Around the World
- Junior Library Guild Gold selection
- Massachusetts Book Award Long List
- Selected as one of 100 Outstanding Picture Books of 2023 by dPICTUS and featured at the Bologna Children’s Book Fair
- Starred review from School Library Journal
- Chicago Library’s Best of the Best
- 2023 INDIES Book of the Year Awards Finalist
- Green Earth Book Award Long List
- Imagination Soup’s 35 Best Nonfiction Books of 2023 for Kids
Amazon / Barefoot Books / Signed or Inscribed by Me
What great projects for kids who like to make things. And, it teaches science.
Hi Patricia,
What is so great about this project is that it’s quick to make and you probably have all the stuff in your house already (if you don’t mind sacrificing a CD case)!
This is a great science project for kids!
Hi MaryAnne,
It’s a fun one, and quick and easy too!
one of my students did this project and had lots fun doing it. I would recommend this small project if you’re bored!
We did these with my mom! They are fun! :o)
Hi Erik,
I’m impressed with your mom! It wasn’t easy to pull off (speaking as mom trying to do it!)
Mom is a scientist 🙂 She is always doing cool stuff like this!
Hi Erik,
Your mom is awesome!! My hat is off to her based on how you are turning out!
Oh, this is awesome! I love learning new stuff! Can’t wait to share with our son. #MMBH
Hi Erin,
It’s fun to build but do get the right size magnets … our first mistake!