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Photo: DER SPIEGEL
You probably know bar magnets from school or from a physics kit.
This makes great tricks possible: For example, you can slide a bar magnet with another bar magnet over the table without them touching each other.
All you have to do is bring the north pole side of one rod closer to the north pole side of the other, because they repel each other.
In the following puzzle, however, there is only one bar magnet on the table.
The second rod is simply made of iron.
He is therefore attracted by the bar magnet.
Unfortunately, you don't know which of the two bars is the bar magnet and which is made of iron.
Both bars are equally heavy.
How can you find out which of the two bars is the bar magnet without any further tools?
You place one stick across the table and push the other stick with one end forward towards the center of the cross stick.
The two bars must be at an angle of 90 degrees to each other.
If the transverse bar does not move at all or only minimally, it is the bar magnet.
Its center between the north and south poles is only weakly magnetic.
If, on the other hand, the transverse rod rolls towards the rod with which you are slowly approaching, the opposite is true: the transverse rod is made of iron, the other is the bar magnet you are looking for.
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