This viscous, highly-colored, reddish brown liquid in a sealed Erlenmeyer flask is attracted to a magnet and forms itself into a spiky mass.
This demo can be used when the magnetic properties of materials are being presented or when nanotechnology is being discussed. This demo takes about two minutes to perform.
Ferrofluids consist of nano-particles of a ferromagnetic material, such as ferrite or hematite, suspended in a carrier fluid with the aid of a surfactant. Ferrofluids are paramagnetic in the sense that they are atttracted to a magnetic field, but cannot themselves be magnetized as ferromagnetic solids can. The spikes form as the fluid tries to minimize the magnetic energy within itself at the expense of increasing the gravitational energy and surface free energy. (Wikipedia, "Ferrofluid." 1/3/07)
- sealed Erlenmyer flask containing ferrofluid
- a strong magnet
- Hold the flask in one hand and carefully bring the magnet into contact with the bottom of the flask. The fluid will be observed to "mound up and spike."
- Move the magnet along the surface of the flask, up the side of the flask. A mounded, spiky mass of the fluid will stick to the side of the flask.
Bring the magnet up to the flask slowly and hold it tightly so that it does not strike the glass and possibly crack it.