Direct-Current Types:

You can make a dc electromagnet by taking a large iron or steel bolt (like a stove bolt) and packaging a couple of hundred turns of wire about it. Such items are available in almost any hardware store. Be certain the bolt is made of ferromagnetic material. (When a permanent magnet "sticks" to the bolt, the bolt is ferromagnetic.) Preferably, the bolt must be at least 3/8 inch in diameter and numerous inches long. You should use insulated or enameled wire, preferably made up of solid, soft copper. The "Bell wire" works well.

Be certain that all the wire turns go in similar direction. A large 6-V "lantern battery" can give abundance of dc to operate the electromagnet. Never leave the coil associated to the battery for more than a few seconds at a time. And do not-repeat, do not-use an automotive battery for this experiment. The near-short-circuit generated by an electromagnet can cause the acid from like a battery to violently boil out, and this acid is hazardous stuff.

Direct-current electromagnets have defined south and north poles, just like permanent magnets. The major difference is that an electromagnet can acquire much stronger than any permanent magnet. You must see proof of this when you do the experiment with a large sufficient bolt and sufficient turns of wire. The other difference among an electromagnet and a permanent magnet is the fact that in an electromagnet, the magnetic field exists only as long as the coil carries the current. Whenever the power source is eliminated, the magnetic field collapses. In some situations, a small amount of residual magnetism stays in the core, though this is much weaker than the magnetism produced whenever current flows in the coil.