Remember those Newton's Cradle executive desk toys? They might be fun to play with, but you can't use them to send a piece of metal careening into someone's face. The Gaussian Gun uses the same principle — but it actually lets you shoot a projectile.
To set up a Gaussian gun, you don't need a lot of equipment, but you do need that equipment to be specific. The first is easy — a simple groove that objects the size of marbles can run along. You can find a pipe or carve a groove into wood, but it's easier, when starting out to just use the groove in a wooden ruler, or the cracks between tiles in a floor or on a counter. You also need ball bearings, because a gun needs bullets, and these will be your projectiles.
Finally, you need at least one neodymium magnet. These are strong magnets, made from a combination of metals - neodymium, iron, and boron. They are so powerful and long-lasting, they've become the standard for power tools and other industrial applications. Neodymium magnets can be a little pricey, but they really make this experiment work. Try to get the kind that are cylindrical.
Tape a magnet on the groove, and on one side of the magnet line up three or four of the balls. On the other side of the magnet, but just a little distance away from it, put the last ball. Roll it towards the magnet.
It behaves a bit like Newton's Cradle, but that last ball takes off at considerably more speed than we put into the first one when we set it rolling. Gravity accelerates Newton's Cradle, but the magnets accelerate the balls in the Gaussian gun, and neodymium magnets are powerful. What we're seeing is the transfer of kinetic energy from the ball rolling in to the one rolling out. If you're wondering why all the balls don't go scattering, consider how much magnetic force the balls right next to the magnet feel versus how much force the ball farthest away from the magnet feels.
As we see, we get a lot of acceleration with one iteration in the Gaussian gun. There are some versions that involve many iterations. The ball that's "shot" from the first magnets hits another magnet and another set of balls. The ball that's shot away from that hits another magnet. Each repetition of the process adds kinetic energy. It's possible to add iterations until the last magnet is shattered by the force of the ball hitting it. At the very least, the Guassian gun can send a "bullet" out pretty fast - so try to keep it to table-tops and floors.
Top Image:Benson Kua