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Friday Puzzle -- find the magnet

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Friday Puzzle -- find the magnet

#1

Friday Puzzle -- find the magnet

Alex Y

On a plywood table approximately 18" square, you have the following objects:

  • One iron rod, 4" long x 5/8" diameter, painted red

  • One iron rod, 4" long x 5/8" diameter, painted green

  • One spool of nylon monofilament thread

  • One old-fashioned 5-1/4" computer diskette

  • One glass beaker with a pint of distilled water


You are told that one of the iron rods is magnetized, while the other is not. Given just the above materials, what is the easiest way to identify the magnetized rod?

Re: Friday Puzzle -- find the magnet

#2

Re: Friday Puzzle -- find the magnet

Bill Earl

I can think of a couple easy ways off the top of my head. If you swapped that water for mineral oil, there are even more interesting ways to identify the magnet.

Re: Friday Puzzle -- find the magnet

#3

Re: Friday Puzzle -- find the magnet

Bill Earl

The absolutely simplest method would only involve manipulating one of the objects.

Re: Friday Puzzle -- find the magnet

#4

 


Re: Friday Puzzle -- find the magnet

#5

Solution

Alex Y

Bill got this one.

Everything but the two bars of iron were red herrings. The simplest solution is to move one bar so that one of its ends is against the center of the other bar (forming a "T") If there is magnetic attraction, the bottom of the T is magnetized; if not, the top of the T is the magnet.

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