Explain Magnetostriction.
Magnetostriction: If ferromagnetic materials are magnetized a small change of dimensions of the material obtains place. There is a small extension along with equivalent reduction of cross-section of the crystals of that the material is made. When this rapidly alternating magnetic fields so there is a rapid and continuous extension and contraction of the material. It is termed as magnetostriction. This magnetostriction is the main cause of hum in transformers and chokes.