The formation of Ditchev’s rings

The formation of Ditchev’s rings

R K W Haselwimmer

Cavendish Lab., Cambridge Univ., UK

R K W Haselwimmer 1992 Eur. J. Phys. 13 145. doi:10.1088/0143-0807/13/3/010


Novel patterns of iron filings (Ditchev’s rings) that seem to defy any classical explanation have been reported earlier. These patterns appear when magnetic powder is floated on a liquid surface above a magnet pole. The author presents more detailed observations that reveal the presence of new open ring and lattice structures. The author then considers the subtle balance between magnetic and surface tension interactions to explain all the observed effects classically. The close packed lattice structures have been modelled by considering the forces on separated magnetic particles in a divergent external field, whilst the ring behaviour has been associated with the formation of short radial filaments under magnetic attraction. When lying in dipped fields these microfilaments crucially generate capillary dipoles, and it is the interaction of these that is thought to produce both open and Ditchev’s ring structures.

28. March 2015 by hrdichev
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