Magnets can be useful in various applications that pertain to our everyday life. They can work as holders for your notes, lists and reminders as well as clips for your bags and sacks. Apart from these, magnets can also be used as Ferro fluids. Ferro fluids are liquids which become magnetized when exposed to a magnetic field. This liquid is actually a colloid which consists of carrier liquid and ferromagnetic particles. The ferromagnetic particles are very small and hence do not settle down. They disperse as soon as the magnetic field is removed. To avoid the formation of lumps which can render the Ferro fluid less effective, the particles are treated with surfactants.
When Ferro fluids are subjected to magnetic fields, they exhibit peculiar physical formations. As opposed to the plain flat surface of liquids, Ferro fluid will organize itself into tiny peaks projecting outwards. This way, the liquid would appear like a solid substance whose surface is composed of peaks and valleys. The dark magnetic fluid, under the influence of a magnet, would become a dome or ball having spikes all over its surface. This peculiar shape is formed in order to attain the minimum energy state. Also referred to as normal field instability, this phenomenon causes the magnetic field to be strong at the peaks and weak at the troughs. Ferro fluids are capable of holding that shape while still remaining fluids. This is not the case with iron ores.
This interesting property of Ferro fluids make them useful for a host of scientific and technological applications. Those who manufacture hard discs, often use Ferro fluids while spinning drive shafts. When a magnet is placed near the shaft, it attracts the Ferro fluid which in turn seals the drive opening, thus preventing foreign particles from making an entry. When used with powerful magnets, Ferro fluids can also work as excellent lubricants in mechanical applications. In medical science the MRI scanning which is used while diagnosing cancer and other diseases, uses Ferro fluids. It is for the same reason that the process is called Magnetic Resonance Imaging. NASA too has tested the use of Ferro fluids in altitude control mechanisms.
One of the widespread uses of Ferro fluid is in loudspeakers where they are kept around the voice coil with the help of the magnet used in the speaker. This allows them to absorb heat and hence work as a coolant without consuming energy from outside. Researches are also being carried out in order to find the applicability of Ferro fluids in the field of heat transfers and optic applications. Just like the loudspeaker, many other devices find it particularly useful to couple magnets with Ferro fluids in order to deliver better performance.
