Currently, there is much emphasis on the study of magnetic
properties of materials. While magnets date back to ancient
times, new techniques have made it possible to use magnets in a
wide variety of applications, as exemplified by flexible
magnets. Perhaps the most common place to encounter flexible
magnets is the refrigerator door in the form of flexible sheet
refrigerator magnets. The common flexible sheet refrigerator
magnet (RM) has a complex, ingenious magnetic structure. The
field lines in the RM are U-shaped; therefore, most of the
magnetic field extends from the back of the magnet and very
little magnetic field from the front. A RM can essentially be
thought of as an array of very small horseshoe magnets. The
magnetic field structure therefore comprises a striped pattern
of alternating north and south poles on the brown, unprinted
side of the RM, with a typical stripe width of 1-2 mm. This
unusual magnetic topography can be used for a number of
interesting demonstrations and experiments. Figure 1. (to