A colloidal suspension of Fe3O4 nanoparticles acts
as a magnetic "liquid" and forms amazing spikes when a magnet
is brought close. The particles act as small compasses marking the magnetic
field lines of the magnet.
The ferrofluid you see consists of magnetic nanoparticles suspended in water. As a magnet is brought up to the ferrofluid, spikes form in the fluid and can dance in response to movements of the magnet. Synthesis of aqueous ferrofluid.
Oil-based commercial ferrofluid is poured into a dish.
Magnets are lowered close to the ferrofluid, and then raised.
Magnets are lowered close to the ferrofluid, and then raised. The ferrofluid
follows the magnetic field lines.
Ferrofluid attracted to a magnet has an apparent density that is large enough to displace a penny.
(This technique can be used for separations. See American Mineralogist, 62, 374-376 (1977).)
A lever raises and lowers a cow magnet between two bottle cells containing water and ferrofluid. (Part of the MRSEC Nanoworld Display.)
A knob turns an array of magnets and ferrofluid in bottle cells respond. (Part of the MRSEC Nanoworld Display.)
