I hope the rest of the advice is better than the advice for magnetizing a compass needle:
If you have a battery and some electric wire, you
can polarize the metal electrically. The wire should be
insulated. If not insulated, wrap the metal object in
a single, thin strip of paper to prevent contact. The
battery must be a minimum of 2 volts. Form a coil with
the electric wire and touch its ends to the battery's
terminals. Repeatedly insert one end of the metal
object in and out of the coil. The needle will become an
electromagnet.
No, the needle will not become an "electromagnet," once it's outside the coil. It won't even become a good permanent magnet if you follow these directions, because you'll tend to demagnetize it every time you withdraw it in the same direction you inserted it. (I actually tried it with a power supply, a spool of wire, and a couple of screws. Dropping a screw through the coil in one direction 10 times will give it the same amount of magnetism that moving it in and out about 200 times will impart.)
In any case, none of this has anything to do with the battery's voltage except to the extent that it provides more current per turn. A 1.5V 'AA' cell would work fine for creating a compass needle unless you wasted your time with those instructions.
But hey, at least now I know that polar bears are best avoided, and that drinking kerosene will get rid of intestinal parasites...
In any case, none of this has anything to do with the battery's voltage except to the extent that it provides more current per turn. A 1.5V 'AA' cell would work fine for creating a compass needle unless you wasted your time with those instructions.
But hey, at least now I know that polar bears are best avoided, and that drinking kerosene will get rid of intestinal parasites...