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. Additionally, 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.
Iron filings are also used to fortify enriched foods for human consumption. However, it is known that pure Iron in it's metallic form is not processable by the human body, it will simply be excreted. It has to be absorbed in another form such as a ferric salt.
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