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  1. The film at the end is [magnetic field viewing film]( It contains a layer of nickel particles in oil.

    The field lines are not the usual dipole field because fridge magnets are actually [Halbach arrays]( Halbach arrays are a specific arrangement of magnets that utilizes the interactions of magnetic flux to double the field on one side while eliminating the field on the other side of the plane.

    The fridge magnets are made by mixing iron particles in a plastic liquid mixture. While the mixture is still a liquid, an alternating magnetic field creates the Halbach array. When the mixture cools and solidifies, the field becomes permanent. Halbach arrays are used in fridge magnets since they are able to create a stronger magnetic field with less magnetic material with the added bonus of the advertising face never being covered up when in use.

  2. Anyone know why the top one has the two roundish “voids” in the pattern? Is there a specific reason, or is it just sloppy/cheap manufacturing?

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