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The article Ferromagnetic material properties is intended to contain a glossary of terms used to describe (mainly quantitatively) ferromagnetic materials, and magnetic cores. ==Terms== *hysteresis loop - induction B as function of field strength H for H varying between Hmin and Hmax; for ferromagnetic material the B has different values for H going up and down, therefore a plot of the function forms a loop instead of a curve joining two points; for perminvar type materials, the loop is a "rectangle" (''Domain Structure of Perminvar Having a Rectangular Hysteresis Loop'', Williams, Goertz, ''J. of Applied Physics'' 23, 316 (1952); in fact it is rectangle if B-µ0H is used instead B on the plot); *remanence Br - "induction which remains" - after magnetization to saturation, a value of induction B in the material in a closed magnetic circuit without external field H; the point where hysteresis loop crosses B axis; *coercivity Hc - after magnetization to saturation, a value of field strength H at which induction B in the material becomes 0; the point where hysteresis loop crosses H axis; *(maximum) energy product (BH)max - largest possible field of a rectangle on the hysteresis loop plot, which has two edges on the B and H axes, and a vertex on the hysteresis loop in the second quadrant (B positive, H negative); range from below 1J/m3 for some soft materials (permalloy, 3E4 ferrite), to above 400kJ/m3 for hard ones (neodymium magnets); *magnetic viscosity - when an external field H is changed, and then kept at a new value, the induction B first changes almost at once, then some smaller change of B follows in a time; for a permanent magnet typically the time dependence is B(t)=B(t0)-S *ln(t/t0), where t is time since H change, t0 is some reference time, and S is a constant of the process (but not of the material, as it varies with magnitude of the H and its change); a theory describing this kind of time dependency was developed by Louis Néel (''J. de Phys. et Radium'', 11, 49 (1950)) and by Street and Wooley (A Study of Magnetic Viscosity, ''Proc. Phys. Soc.'' A62. 562 (1949)). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ferromagnetic material properties」の詳細全文を読む スポンサード リンク
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