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The change in shape and density of a substance, especially a ferromagnetic substance, when exposed to a magnetic field. The change depends on the direction and strength of the magnetic field. Rapid, alternating magnetostriction causes the iron cores of household transformers, which are subject to a changing magnetic field, to hum or buzz.
change in the dimensions of a ferromagnetic material, such as iron or nickel, produced by a change in the direction and extent of its magnetization. An iron rod placed in a magnetic field directed along its length stretches slightly in a weak magnetic field and contracts slightly in a strong magnetic field. Mechanically stretching and compressing a magnetized iron rod inversely produces fluctuations in the magnetization of the rod. This effect is utilized in nickel magnetostriction transducers that transmit and receive high-frequency sound vibrations. A bent iron rod will straighten a bit in a longitudinally directed magnetic field, and a straight rod carrying an electric current will twist slightly in a magnetic field.