The non-homogeneous mix of magnetite, iron, oxygen and other trace elements in lodestone, the only naturally occurring magnet, is what makes it permanent (hard). Pure homogeneous magnetite or iron is not permanent but a temporary (soft) magnet. An ideal permanent magnet is a heterogeneous alloy with high coercivity, meaning it is difficult to demagnetize. These alloys have elements with atoms that can be induced to point persistently in the same direction (ferromagnetic) making them strongly magnetic. Only three--iron, cobalt and nickel--of the 100 elements in the periodic table are ferromagnetic at room temperature. Alloys are made magnetic by exposing them to magnets or electromagnets.
Things You'll Need
- Loudspeaker magnet
- Steel nail
Video of the Day
Extract a permanent magnet from a loudspeaker.
Use tongs to heat the steel nail over a stove, allowing atoms in the nail to move around more freely.
Use the compass to determine the Earth’s magnetic north and south poles. Align the steel nail in the North-South direction and place the loudspeaker magnet just north of the nail.
Hit the nail with the hammer until it is cool, at least 50 times, making sure the nail remains all the while in the north-south direction. The atoms within the steel nail will be shaken to line up with the magnetism of the nearby magnet.