Dipole Magnet and Iron Filings http://physicstoys.blogspot.com/p/physics-toy-store.html Visualizing the invisible- the magnetic field lines around a dipole magnet. In the presence of a magnetic field, ferromagnetic materials (such as iron) temporarily become magnets. Here the iron filings become dipole magnets and link end to end to follow and reveal the magnetic field lines associated with the permanent magnet within the hollow tube. ➡️ Follow the link above for info on where to buy this and ot