Inside the classroom, the magic of magnetism can be quickly lost to complicated charts and technical assignments. But there’s no shortage of compelling projects you can complete with your students to explain and demonstrate how magnets work without ruining the fun.

Today’s example: The magnetic linear accelerator. Also called the Gauss gun, it takes its alternative name from Carl Friedrich Gauss, a brilliant German mathematician who contributed to a number of fields, including magnetism. Creating a magnetic linear accelerator is an excellent project for a physics class of any level. This experiment not only demonstrates magnetism, but also the principles of momentum and the transfer of energy.

Materials for Your Gauss Gun

There are myriad ways to make a Gauss gun, but here are some easy-to-access materials you can safely use in the classroom:

  • 1 wooden ruler with a groove along the center
  • 3 ½” x ½” x ½” neodymium cube magnets
  • 7 ⅝” ball bearings
  • Tape
  • Scissors
  • Safety goggles or glasses

It never hurts to have extra supplies on hand so students can either make their own or complete the project in groups.

Directions for Your Gauss Gun

To make a magnetic linear accelerator, you and your students will need to:

  1. Tape the wooden ruler to a table, groove side up, to prevent flopping around while using the magnets.
  2. Tape the magnets along the ruler’s groove 3 inches apart. Cut off any excess tape.
  3. Place two ball bearings on the right side of each magnet so they’re seated in the groove.
  4. Place the remaining ball bearing on the left side of the ruler along the groove.
  5. Bump the far-left ball bearing towards the first magnet, and watch the chain reaction!

What should happen: The first ball bearing will snap against the first magnet. In the blink of an eye, the energy from the first ball will shoot the other bearings against the other magnets, eventually sending the last bearing flying off the ruler.

Important: Always wear proper safety goggles or glasses during lab experiments.

How it works

When that first ball bearing hits the magnet, its kinetic energy is transferred through the magnet into the ball bearing on its right. The energy then flows into the next ball bearing, pushing it along the groove — sort of like Newton’s Cradle. When an end ball swings in Newton’s Cradle, it smacks the next ball in line. The energy passes through each ball in the line until it sends the last ball swinging.

The process repeats itself. The third ball bearing speeds into the next magnet. Its kinetic energy, which is now larger than the first magnet, transfers through the magnet and the next bearing, sending the fifth ball bearing soaring. The fifth ball bearing smacks against the third magnet, transferring energy through the magnet and the sixth ball bearing, sending the seventh ball bearing off the ruler.

Taking It to the Next Level

If you want to make the project even more creative for your students, have them experiment with the design. They can use a different number or size of bearings or magnets, different track material or length, or they can adjust the spacing between magnets.

From there, students can tinker with the design until they’re ready to see whose Gauss gun shoots the fastest and whose shoots the farthest. As your students experiment, have them track how changes impact the efficiency of their magnetic linear accelerators. Ask them to explain why those changes took place.

If you’d like to have your class build multiple magnetic linear accelerators, you’ll need a good number of magnets. Browse our catalog of cube neodymium magnets to get started.