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These experiments are really cool, and students love 'em! Better yet, they're cheap! Neodymium (knee-oh-dim-ee-um) magnets are used in this experiment, hereafter referred to as "NIB" magnets. Huh? Where does the B come from? Neodymium isn't the only material in a NIB magnet. NIB stands for "Neodymium Iron Boron," the elements combined to form the magnet.

NIB magnets can be hazardous however, so caution is needed. NIB magnets are VERY fragile, and if allowed to come together with any force at all they will shatter. I NEVER allow students to use more than one super magnet at a time, and have them wear goggles while doing so. Even if they don't shatter, they can give you a good pinch. I set up an area free of ferrous metals for students to work in, which is tougher to arrange than it sounds. Even the screws and nails in furniture will grab those NIB magnets from your hand! Furthermore, NIB magnets MUST be kept away from magnetic field sensitive things, like computers, stereos, credit cards and so on. I carry mine in a small box with a loop of sheet metal inside, and keep the magnets nestled in the center with newspaper. I use ½" and ¾" NIB sphere magnets obtained from FORCEFIELD.

The first experiment never fails to elicit an amazed response from the students. I show them a 4' piece of copper pipe, and assure them that there is nothing unusual about it, just standard hardware store copper pipe. I show a ½" steel ball bearing (BB), and ask how long they think it will take for it to drop through. I then have them count off the seconds when I drop the BB. Of course, it takes a second or less to fall through. I then show the magnet and introduce it, and walk around the class showing everyone that the magnet is indeed smaller than the pipe, and fits easily. I make sure they see that magnet is not attracted to the copper pipe. I ask how long they think it is going to take to drop through and then again have them count off as I drop the magnet. It takes about 10 seconds for the magnet to drop through!

In the next experiment, I have pairs of students drop a ½" NIB through a 18" section of ½" copper pipe. (note: I also use ¾" NIBs and ¾" pipe) Students drop the magnet through the pipe, and watch it fall. They see it slowly sink, rarely if ever touching the sides!

This experiment uses a trough I made out of an old piece of aluminum sheet metal. I expect a piece of angle flashing would work well. Students are given the trough, a NIB and a marble. Don't use a BB, they will stick together. Have them roll the magnet and the marble back and forth, trying them separately and together. Of course, the students will observe that the magnet moves much more slowly than the marble.

How does it work? When the magnet drops, it's magnetic field creates an electrical current as it moves through the pipe. Since the pipe now has an electrical current running through it, it becomes an electromagnet. The electromagnetic field interacts with the magnetic field of the NIB, slowing its fall. The same thing is occurring with the trough experiment. Very neat indeed!