Final answer:
Iron filings align with a magnetic field due to induced magnetism. This happens as the domains within the iron filings align with the external magnetic field when in proximity to a magnet or a current-carrying coil, making the filings temporary magnets.
Step-by-step explanation:
Iron filings align themselves with a magnetic field due to induced magnetism. This occurs because iron is a ferromagnetic material, which can become a temporary magnet when it is in the presence of a magnetic field. The magnetization of iron filings happens at the microscopic level, where regions called domains contain atoms with their own tiny magnetic fields. When not under the influence of an external magnetic field, these domains are randomly oriented. However, when exposed to a magnetic field, as when near a current-carrying coil or a permanent magnet, the domains begin to align with the external field.
This phenomenon is visible when you sprinkle iron filings on a piece of paper above a magnet and observe how the filings form patterns that trace the invisible magnetic field lines, similar to how compass needles would align. The iron filings, therefore, act as tiny compass needles, responding to the magnetic influence and visually revealing the shape of the magnetic field around the magnet.