Iron filings

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Iron filings are very small pieces of iron that look like a dark powder. They are very often used in magnetism demonstrations, to show magnetic lines. Since iron is a magnetic material, it will align itself with the magnetic lines of a magnet in the same way a compass will align itself with a magnetic field.

[edit] History

Main article: History of ferrous metallurgy

Filings are mostly a byproduct of the grinding, filing, or milling of finished iron products, so their history largely tracks the development of iron. For the most part, they have been a waste product.

Iron filings have some utility as a component in primitive gunpowders. In such a fine powdered form, iron can burn, due to its increased surface area.

In modern electronics, some magnetic applications use iron powder cores for transformers.

[edit] Uses

The primary use of iron filings are in the study and teaching of magnetism and electromagnetic fields. The substance makes very impressive demonstrations when used on a blank surface. It is found in the childhood toy that involves a magnetic pen with which one can write. By sprinkling fine iron on a magnetic stripe, it is possible to see the magnetic encoding on such stripes. In addition, by suspending iron filings in a semi-viscous fluid, and pouring them directly on to the platter of a hard-drive, the patterns of bits will clearly show in the alignnment of the iron filings.

[edit] Manufacture of Iron Filings

It is possible to create iron filings at home by filing a ferro-magnetic lump of iron or steel.