What you will need:
1) copper pipe (approximately 18” in length – preferably ½” in diameter)
2) Rare earth magnets – small enough to easily fit inside your copper pipe
3) Adult supervision
CAUTION: Magnets can be deadly around young children. Please do not leave magnets unattended or where small children could swallow them.
Hold your copper pipe in a vertical position. Insert your magnets into the top opening of the pipe and let them go. They should drop slowly through the pipe as if they were going in slow motion.
What is going on?
By Lenz's law, an eddy current creates a magnetic field that opposes the magnetic field that created it. Eddy currents that are induced in the conductive surface of the copper pipe by the moving magnetic field exert a drag force on the moving magnet opposing its motion.
Try dropping your magnets through a plastic pipe. Does it react the same? What if you drop it through a steel pipe? What happens then?