Magnetorheological Fluid

In a beaker is 250 milliliters of corn oil to which has been added about 0.5 kilogram of iron filings about 1 millimeter long. The mixture is stirred thoroughly and a strong horseshoe magnet is brought up to straddle the beaker. The iron filings align with the magnetic field as expected to magnetize the fluid mixture. What other physical property of the fluid changes?

Answer

The flow properties of the fluid change so radically that the fluid becomes gel like and can be pushed to one side of the beaker where no relaxation may occur. The degree of solidification depends on the inherent properties of the fluid and the strength of the magnetic field. Of course, its solidification may vary within the gel itself because the magnetic field may vary with position in the beaker. Practical applications of these materials with their unusual properties are being devised and tested. Perhaps automobile braking systems may someday use these types of fluids to replace solid materials that wear away.