OK, a puzzle this time. Imagine that you have two steel bars that look alike. One is a magnet and the other is not. Without using anything else (No paperclips, iron filings, etc.) how would you be able to tell which is the magnet?
Answer:
If you bring the ends together, they will stick, even if only one bar is a magnet. The trick is to remember that the magnetic field of a magnet is strongest at the north and south poles. The middle of a bar magnet is very weakly magnetic. Bring the end (either north or south pole) of bar 1 up to the middle of bar 2. If it sticks, then bar 1 is the magnet. The strong attraction of the end of the magnet sticks to the middle of the other bar. On the other hand, if it does not stick, then bar 2 is the magnet. You can test that by bringing one end of bar 2 near the middle of bar 1. The end of a magnet will attract the middle of a steel bar, but the end of a steel bar will not be noticably attracted to the middle of a magnet.
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