When a ferromagnetic material is placed in an alternating magnetic field, the flux density (B) lags behind the magnetizing force (H) that causes it. The area under the hysteresis loop is the hysteresis loss per cycle, and is high for permanent magnets and low for high-permeability, low-loss magnetic materials.
Magnetic Hysteresis Loop
Coercive Force Hc
Has to be applied to reduce the flux density (B) to zero.
Hysteresis Work Wh
The energy dissipated during a single cycle of the hysteresis loop. This is equal to the product of area of the hysteresis loop (Wh) and core volume (Viron).
Remanent-flux Density Br
The residual magnetism of flux density (Br) remains in the iron core after the external magnetic field strength (H) is removed.