My latest assignments at the museum included a cool little activity with magnets. I had to design a method for getting magnets to float at neutral buoyancy and maintain a consistent orientation to make a workable demonstration of how magnets attract and repel each other along their poles. My design trials were somewhat cumbersome and ultimately flops (literally) until I mastered a genius contraption incorporating water bottle caps and foam core pieces.
The activity demonstrates how magnets will repel each other when aligned so that their similar poles are oriented together. The magnets float in water and as each new magnet is introduced to the surface of the water, it “pushes” other magnets out of its way. Eventually, the magnets will arrange themselves in geometrical patterns to achieve the greatest distance between each other. It’s pretty cool, but creating the right floating device is tricky. The magnets need to be buoyant enough to not flip over and attract the opposite poles of other magnets, which would defeat the entire demonstration.
In this video, you can see the design that worked out the best, and the neato effect of the magnets on each other. You can see how magnets push each other out of the way as they are introduced to the surface of the water, and then realign themselves when some are removed.
More ideas for this activity: what happens if you put more than one magnet in the bowl at once? What happens if you try to flip magnets over and re-orient the poles so that opposite poles are in the water at once? How many floating magnets can you get in one bowl and what shape do they align themselves in?