- Iron filings
Iron filings are very small pieces of
iron that look like a dark powder. They are very often used in science demonstrations to show the direction of amagnetic field . Since iron is aferromagnetic material, a magnetic field induces each particle to become a tinybar magnet . The south pole of each particle then attracts the north poles of its neighbours, and this process repeated over a wide area creates chains of filings parallel to the direction of the magnetic field.History
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
transformer s have iron powder cores.Uses
The primary use of iron filings is in the study and teaching of magnetism and electromagnetic fields. The substance makes impressive demonstrations when sprinkled on a white card placed on top of a permanent magnet. The filings are also found in toys that allow one to draw with a magnetic pen. By sprinkling fine iron on a
magnetic stripe card , it is possible to see the magnetic encoding on the stripe. Another demonstration is to pour onto the exposed platter of a hard drive a semi-viscous fluid in which iron filings are suspended, so that the patterns of bits on the platter are revealed by the alignment of the iron filings.Fact|date=September 2008Manufacture of iron filings
It is possible to create iron filings at home by filing a lump of iron or steel.
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