When electricity creates a magnetic field, it can do all kinds of things: move the clapper in your doorbell to make it ring, turn the motor in your electric car, even make the inside of your body visible to doctors when you are sick or injured.
That same force can power a train, like the Hyperloop and maglev trains being developed and used in some parts of the world. But you don’t have to travel to China or wait 10 years—you can make your own electric train with a few simple materials.
Please note: This activity is targeted to older children because of the use of small and powerful magnets. (Learn more about why these can be dangerous for young children.)
You will need:
- uninsulated copper wire
- a dowel, for winding the wire around to make your coil
- one AA battery
- two rare earth (neodymium) magnets—these must be slightly larger than the battery, but small enough to glide through the coil. We recommend using 5/8 inch dowel and 5/8 inch magnets.
- Wind the coil around the dowel until you have a nice long coil. (This video shows a fun way to get it done quickly with a power drill!
- Assemble your train by placing one magnet on either end of the AA battery.
- Place your assembled train at the opening of the coil. If it doesn’t move, you may need to turn one of the batteries around (more on that below).
CAUTION: Neodymium magnets are VERY strong. Keep them separate from each other and away from other items. They are quite powerful when attracted to each other and can pinch fingers that get in the way. Young children and people with pacemakers should NOT play with these magnets.
What’s happening here?
With a magnet connected to each end of a battery, when both magnets touch the wire coil, an electrical circuit is completed. As the electric current flows through the copper coil, a magnetic field is created. This magnet field repels the magnet fields of each magnet, attached to the battery. Because the battery/magnet ‘Train’ is free to move, the repelling fields push the ‘Train’ down the coil. As the ‘Train’ moves, the magnet field in the coil moves with the ‘Train’.
Why does it matter which way the magnets are turned?
In a magnetic field, the north pole is pushed in one direction and the south pole is pushed in the other direction. But because every magnet has both, pulling against each other, you need to make sure that the battery is working on matching poles (i.e., both north poles or both south poles are attached to the battery). The easiest way to do this is to hold the magnets together—when you have made them repel one another, just place the battery in between.
By having the battery power connected to matching poles, you can make sure it’s sending the train in that direction—not powering both directions against each other so it just stands still. If you find that it’s actually powering your train out of the coil and back toward you, just turn it around—it should zoom right in.
