Re: would an iorn rod wacked against a fire hydrant make a magnet

I also like MacGyver.

I answered this question a few years ago by doing the following experiment. I went to Home Depot and got a big 12 inch long iron spike, a great big nail. I made sure it was not magnetized. I lined it up with the earths field which is down about 60 degress from horizontal and pointed north of course. I then hit it as hard as I could with a hammer about a dozen times. It was then magnetic enough to pick up a paper clip!!

What is happening is that iron is somewhat magnetostrictive. That is, the direction it wants to be magnetized depends on stress. When you stress it by hitting it the magnetic domains move around. If the spike is parallel to the 0.6 Oe field of the earth the domains move so that the spike is partially magnetized.

Check out my book Mondo Magnets on the web. It has a lot of other magnetic magic tricks in it. There is also a DVD by the same name of my magnetic magic show available from Supermagnetman.net.

Good luck!

Fred Jeffers