Iron filings

Iron filings are very small pieces of iron that look like a light powder. They are very often used in science demonstrations to show the direction of a magnetic field. Since iron is a ferromagnetic material, a magnetic field induces each particle to become a tiny bar magnet. The south pole of each particle then attracts the north poles of its neighbors, and this process repeated over a wide area creates chains of filings parallel to the direction of the magnetic field. Iron Filings are used in many places including schools where they test the reaction of the filings to magnets.