easiestway to determine the polarity of the unmarked magnet - use marked. As a rule, the north pole of a magnet noted blue paint, south, respectively - red. Since like poles repel each other and opposite charges attract each other, it is enough to see what pole of your magnet will be repelled from the north polereference, to determine where some.
For the same purpose, you can use the compass, which, in essence, is a magnetic needle, freely rotating on the axis. Hold a magnet to the compass and see to whathis pole is attracted northern end of the arrow.This will be the south pole of your magnet.
If you do not, and compass, you can make yourself, but it will require the ability
to navigate the terrain.After a few times of the magnet iron needle, you magnetize it.Then, lubricate the needle in any oil, put it on the surface of the water, poured into a saucer.If saucer wide enough, and not near strong magnets, the arrow indicates one of its ends to the north.To determine where the north and the south where you can, for example, the sun - in the northern hemisphere, it is most of the year moves on the south side of the sky.Then you can check the polarity of the magnet in the same manner as with an ordinary compass.
force field lines enter the south pole of the magnet in and out of the north, as it were gyrating.Electric charge, appeared in this field, will follow the movement of the lines.

pour a little powdered sugar into a clean, dry plastic jar, close it, and how to shake it until the powder does not become charged and begins to stick to the sides of the jar.So you get a positively charged dust.

Put a magnet on the table so that the poles were in a horizontal position.The magnet of the speaker, for example, it will have to put on an edge.Then pour a little of the charged dust in the air above the magnet.Dust will twist along the field lines.