You have two identical looking metal bars. One of them is a magnet, with North and South ends. The other is simply an iron bar (which is attracted by magnets).
How can you tell which is which, using only these two bars?
(1) Attempt to magnetize one bar with the other, as described in the Hutchinson Encyclopedia: "The pole of a bar magnet is placed on top of one end of the steel bar. The pole is then drawn along the length of the bar, keeping the pole in contact with the bar. As the magnet reaches the end of the bar it is lifted and moved with a looping motion back to its starting position. The bar is stoked in this way 10 to 15 times." If after trying this, there are poles of the two bars that repel each other, then the bar used as the magnetizing agent was the original magnet. This solution has the drawback of leaving you with two magnetized bars, instead of one.
(2) Point one bar perpendicular to the other, and see if it is more strongly attracted to the North and South poles of the other bar then it is to the middle portion (assuming you could determine this by sensing that they pull more or less strongly to each other). If this is the case, since a magnetic bar has the strongest magnetism at its poles, this will indicate that the bar being pointed at is the magnetic one.
Edited on January 25, 2005, 3:52 pm
Posted by Penny
on 2005-01-25 15:47:44