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Name: Marc De S.
Status: educator
Age: 50s
Location: N/A
Country: N/A
Date: 1/9/2004

I have been teaching science for 29 years and I found something I find unable to explain. A student in one of my 8th grade classes brought a magnet to me, claiming there was something wrong with it. Being skeptical, I asked what could possibly be wrong with this magnet. He showed me. I have a small cylindrical bar magnet that has the same pole at either end! This is baffling me and all of my students. I told them I would find out what is going on. HELP!

Probably it is two smaller magnets glued together N to N or S to S.

Tim Mooney

At face value this is pretty strange. How did you determine the bar had the same pole at either end? I could imagine doing this by cementing two poles of a magnet N to N or S to S with adhesive. Or possibly the N and S poles are radial and not axial. You can get some further data by placing the bar under a sheet of paper and sprinkle with iron filings (If you have not done this.).

Vince Calder


I can think of two possibilities right off the bat: One is that you have a quadrupole magnet, two north poles and two south poles. Two like poles are at the ends and two of the other pole are near the center. See whether the center of the magnet repels the pole that the ends attract. If so, you probably have 4-pole magnet. Another possibility is that the cylinder is weak compared to the magnet with which you test it. Placing a strong magnet near a weak magnet can temporarily reverse the weak magnet. Place the cylinder in contact with the magnet it attracts. While in contact, see whether the opposite end of the cylinder still behaves the same as before. Does it still attract the same pole? If not, the cylinder is probably reversing. This is what happens to a piece of metal that is not magnetized. There may be other possibilities, but these are the first two that come to mind.

Dr. Ken Mellendorf
Physics Professor
Illinois Central College

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