TOYS, TRICKS, & TEASERS
By Donald Simanek
The Penetrating Magnets Illusion
“Magnets are fascinating things, and they behave in unexpected
ways. I will show you a little-known property of magnets, which
actually allows them to pass through one another.”
Thread 5 of these magnets, with alternately
opposing polarity, on a ¼"-diameter aluminum or A
plastic curtain rod about 3' long, as in Figure A.
» Back in 2004, I invented a physics toy using
magnets, one I hadn’t seen described elsewhere.
So I called it Simanek’s Penetrating Magnet Illusion.
It obeys Newton’s laws, like the others, but why
should Newton get all the credit?
This toy is inexpensive and absurdly easy to build.
Find a dozen small, flat ceramic magnets, 1" diameter,
¼" thick, with a 2" hole in the center. You can get
them at RadioShack or hardware stores. You don’t
need a full dozen, but extras are good to have.
You can get the rod at the hardware store. Don’t use Your claim seems to have actualized: 1 magnet
a steel or iron rod. Plastic is good, but it should be seems to have gone all the way through, and the
smooth and rigid. A wooden dowel is not as good, rest are in the same positions as before (Figure B).
unless sanded very smooth, and perhaps varnished. Now say, “Maybe you didn’t see that, it happened
I put rubber washers or corks on the end of the so quickly.” Reverse the action, by taking the one
rod, so the magnets won’t slide off. that “passed through” and propelling it back toward
For a magic trick routine, you might begin this the others. Same result: the others don’t seem to
way: “Magnets are fascinating things, and they budge, but everyone hears as it “goes through.”
behave in unexpected ways. I will show you a little- Someone will probably suspect that the magnets
known property of magnets, which actually allows just changed positions somehow. So this time, start
them to penetrate through one another — under with the magnets in the center, equally spaced
proper conditions, of course.” except that you enlarge the spacing between 2 of
Now hold the rod in a horizontal position. Spread out them. Tell everyone to watch that larger gap. Do it
the magnets in the middle, so they’re about equally again, and after the magnet passes through, the
spaced, and jiggle the rod so they find a position they larger gap is still there, as shown in Figure C.
“like.” (This spaces them so their magnetic repulsion Yes, you will occasionally crack a magnet, or knock
is just about equal to their sliding friction.) Move the a chip out of one, so have extras on hand. When
magnet at the left end away from the others, and then this happens, just say, “Sometimes, if the atoms
with 2 fingers behind it, propel it forcefully toward the aren’t all perfectly aligned, they can’t quite squeeze
others, so it hits with enough speed that you hear at through the spaces between them, and one magnet
least 1 collision. is so stressed that it cracks.” After discarding those
Before doing it, say that you’re going to make it “pass that chip or break, the remaining ones are probably
right through” the others without disturbing their the sturdiest (survival of the fittest?).
positions. Suggest to the spectators that they watch This demo is more fun than the Newton’s Cradle
carefully the positions of the magnets. Now do it. toy, and a lot easier to adjust. You do need to
Photograph by Constance Simanek
166 Make: Volume 15