Hysteresis

—A peculiar quality of an iron core, such as an armature core undergoing rapid reversals of magnetism, by which Hysteresis there occurs an expenditure of energy which | simeter. is converted into heat. ‘This lo of energy hysteres is due to the work required to change the position of the molecules of the iron, and takes place both in the proce of magnetizing and demagnetizing; the magnetism in each case lagging behind the force; static hysteresis as distinguished from viscous hysteresis. Ewing gives the value in ergs for the energy di ipated per cubic centimeter, for a complete cycle of doubly reversed, strong magnetization, viz.: Very soft annealed iION... 6.6...ee 9,300 ergs Le Aon adler aa aLOO Hard drawn steel wire........++-+. 60,000 “ 06 Hysteretic Lag. a d Annealed steel wire............... 70,500 ers ed Same steel gla bhard ia. o enre see 76,000 A Piano steel wire, normal temper....116,000 4 Same annealed o yn) ane eee 94,600; Same, gla bardim doder ates. eee 117,000 “2 3 Hysteresis Coefficient or Constant.—_! The amount of energy lost in magnetizing and demagnetizing a unit volume of mate a is the hysteresis coefficient of the material. if