why and how does ferrofluid create spikes when attracted to a magnet?
In: Physics
Ferrofluids get their name because they contain iron particles. Ferrum if Latin for iron, so anything that Hass ferro is its name probably has something to do with iron.
The spikes you see when you put a magnet near Ferrofluids results from the iron particles trying to align themselves with the magnetic field of the magnet.
Magnetic fields operate on field lines. So, instead of imagining a magnetic field as a sphere, or hourglass shape, imagine it more as something like this: [https://ds055uzetaobb.cloudfront.net/brioche/uploads/MUtOQWcxPp-magneticfieldlines.png?width=1200](https://ds055uzetaobb.cloudfront.net/brioche/uploads/MUtOQWcxPp-magneticfieldlines.png?width=1200)
The spikes are literally the fluid being attracted to the magnetic lines. We just don’t notice this with solid magnets because we can’t see it.
When placed in the magnetic field, the tiny iron particles in the ferrofluid become magnetized themselves, in the same direction as the external field. This actually causes the field strength to increase around each particle, and therefore makes all of the particles slightly attracted to each other. This creates an instability where the areas with more particles become more strongly magnetized, attracting more particles, becoming more strongly magnetized and so on. This goes on until you either max out the field strength the iron can produce, or deplete the surrounding area of iron particles. Either way, this creates alternating areas of low and high iron density, which we see as spikes.
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