Did you know that electricity and magnetism are closely linked? In this project, experiment with the interplay between the two by building your own miniature electromagnetic train that zips down a track all by itself. Be sure to check out the video instructions for an explanation of how it works!
How we did it:
- 20 gauge copper wire
- aaa battery (1)
- neodymium magnets (6) - 12 mm diameter
- wooden dowels - 1/2 inch diameter
Gather your materials!
Take one end of the copper wire and tape it to the dowel. Begin winding the copper into a coil, making sure the coils are as tightly packed as possible but do not overlap.
Keep winding until you have created a coil that's at least 5 inches long.
Remove the coil from the dowel, and stretch it out just enough so that each winding on the coil doesn't touch the one next to it.
Make two stacks of 3 neodymium magnets. Orient the stacks so they repel each other, and stick one stack to each side of the battery.
Be very careful with these magnets and keep them away from small children! They can be very dangerous if swallowed.
This project won't work with regular magnets like you'd use on a noteboard. We ordered these online.
Slide your train into the copper coil. It should zip down the coil and out the other side! If your train doesn't move, try flipping the train around. If it still doesn't work, try flipping one of the stacks of batteries around.
Experiment by adding or subtracting the number of magnets, or making a longer coil. With a long enough copper coil, you'll be able to make a circle that the train zips around continuously!
What's going on?
Try this. Grab a couple of fridge magnets and flip them so they repel each other. If you place one on a table and bring the other one close, the magnet on the table will slide away. That same magnetic push is what moves your train!
How? Well, placing the battery inside the coil of wire creates an electrical circuit. (In fact, it creates a short circuit, which is why the battery burns out so quickly in this experiment.)
And here's the part where the connection between electricity and magnetism becomes important. An electric current creates a magnetic field. In fact, a coil of wire like you made here creates a magnetic field very similar to the magnetic field of a plain old bar magnet.
Now, the neodymium magnets have their own magnetic field, and they're sitting right in the middle of the wire's magnetic field. And just like a couple of fridge magnets, those magnetic fields interact with each other. That's where the push that propels your train comes from. The neodymium magnets get pushed along by the magnetic field of the coil of wire.