Demagnetization curve

Magnetic characteristics found in the second quadrant of the hysteresis loop is often referred to as a demagnetization curve. Motor’s performance can be worked out from the magnet shape and operating points in this region, where the directions of magnetic field intensity H_m and magnetic induction B_m oppose each other, The intersect value with the vertical axis is called remanence (B_R), while that with the horizontal axis is the coercive intensity or strength (H_m) of the magnetic material. When H_m is increased in negative polarity B_m begins to fall quickly; this operating points is called a knee.