I know that opposite poles attract and similar poles repell but if you had a small magnet that didn’t have it’s poles labeled, how would you figure out which side is negative and which is positive?
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One method you could use to determine this is to make a compass. Most likely your magnet is too heavy to do this but you can use it to magnetize something light like a pin or paperclip. This you can float on the surface of still water and it will orient itself according to the Earth’s magnetic field. The north pole is negative and the south pole is positive.
Remember that opposite magnetic fields attract and similar repel, so whichever end of the floating compass points north is the positive pole. You would then take your original magnet and see which end attracts that positive end of the pin or paperclip and that would be your magnet’s negative pole.
Of course if you were planning to use your found magnet to make a compass you have sort of gone full circle and needed to already know what you were trying to figure out.
I think you mean North and South, not positive and negative, and the easiest way is to allow the magnet to spin freely and see which way points North. That’s the North end of the magnet (and FWIW the North geographic pole of the Earth is actually the South magnetic pole)
You can use Earth’s magnetic field if you know where the North direction is. Put in on something that floats and then on water, it will align itself.
You mean north and south.
Take the magnet, put it on top of a flat styrofoam boat, and see what way it points when it floats. The north end of the magnet faces north.
If you have an electron gun (such as an old cathode ray tube), you can examine which way the beam is deflected by the magnet’s field and use that to determine the poles of the magnet. If the beam is pointed to your left, and the north pole of the magnet is placed close to it pointing away from you, the beam will be deflected downward. The south pole will deflect it upward.
This method is interesting because it does not require you to know anything about which way is north (or even be near a planet with a magnetic field at all).
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