- A magnet is any material or object that produces a magnetic field. The magnetic field is invisible but attracts ferrous metals including iron and steel. In addition, any object with a magnetic field will either attract or repel other magnets. Not all magnets are permanently magnetized. Hard metals and commercial magnets are permanent magnets that have often been superheated to create a more lasting magnetic field, while other metal objects (such as non-super-heated iron) can be temporarily magnetized but then lose their magnetic field some time after they leave the proximity of another magnet.
- Electromagnets are a special kind of magnet that can be easily turned on and off by a switch. Generally speaking, an electromagnet is a coil of wire that produces a magnetic field when electric current runs through it but ceases to be magnetic when the electric current stops. This allows for easy use of electromagnets for experiments, because the magnet can be simply turned off when the experiment is done. This makes it easy to retrieve formerly magnetized objects such as iron filings.
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The magnetic field of a magnet is actually generated by the alignment of electrons within the atomic structure of the magnetic material. All objects contain atoms, and these atoms contain electrons that move around in orbits with a certain spin. The movement of any electron in this manner creates a tiny magnetic field. However, most electrons in atoms exist in pairs. The two electrons in a pair always spin in opposite directions, with the result that the magnetic fields cancel each other out, and no magnetic field is created from the object itself.
Atoms of magnetic materials, on the other hand, contain unpaired electrons with the same spin that aren't canceled out. If a material has enough unpaired electrons with the same spin--such as the four unpaired electrons in an atom of Fe (iron)--and doesn't contain any unpaired electrons with opposite spin, the net movement of electrons in one direction will create a magnetic field.
