This is another great video by Lori Gardi aka Fractal Woman in her quest to demystify magnetism. This time she analyzes the magnetic field patterns associated with a ferrocell, pure ferrofluid, and comparisons with different types of magnets and light sources. The ferrocell involves a thin layer of a mixture of a few drops of ferrofluid with a separating agent, usually very penetrating oil. Lori demonstrates that the pattern is light source dependent and is the first that I have seen to show the ferrocell pattern of a cylinder magnet with a hole drilled into it. This special type of magnet has a similar pattern to a typical cylinder magnet and is in stark contrast to the the typical ring magnet, which involves drilling a hole in a cylinder magnet before magnetizing. Interestingly, the hole-cylinder magnet shows the same polarity reading in the hole region while the ring magnet has an opposite polarity reading in the hole part (i.e. relative to the typical polarity of the magnet itself). This is some truly fascinating examination of ferrocell patterns, as well as pure ferrofluid patterns, so make sure to watch it!
