I have a 5-foot long piece of steel, 15-20 pounds and 1 1/2 inch in diameter, that I use for prying stumps and rocks and whatever. It’s hard as hell, I’m guessing high-carbon steel, and I think in its former life it was some kind of axle or drive-shaft.
If I were to suspend this bar from a rope, align it to magnetic north, then slam one end with a sledge hammer, would it become magnetized? Would it matter if I hit the north or south end? Would I have better results using a softer metal, say a section of re-bar?
Why not wrap it with a copper wire around it’s axis and connect both ends of the wire to a car battery and leave it sit pointing north/south for a week? North being the positive battery side, south being the negative. After the car battery has discharged through it in the right direction, it should be charged pretty damn well and stay that way until a major blow.
That depends on which way you wind it. To figure out the direction of the magnetization, curl the fingers of your right hand around the bar in the direction that the current is flowing (from positive to negative). Your thumb is then pointing towards the north-seeking end.
As to your original method: Probably not. You might get some results from just letting it sit for a long time, though. Iron desks and the like often become magnetized from the Earth’s field, after several decades. Soft iron is easier to magnetize than steel, but it’s also easier to demagnetize, so if you want this thing to be more-or-less permanent, go to the extra trouble to use steel. Of course, if you want to use it for a huge compass, then you’re going to have to figure out some clever torsionless suspension for it, or it won’t turn freely enough. Good luck!
I have heard before that striking a bar while it’s aligned with the Earth’s magnetic field will result in the bar being magnetized. The explanation was that striking it allows the magnetic domains to reorient themselves, and they tend to align with the prevailing magnetic field. Why not give it a try, and let us know?
If you decide to try the wrapping it with copper wire technique, I’d suggest giving the bar a few whacks while the current is running, to speed up the process.
