Explain the hysteresis loop of a magnetic material.

Hystereses loop-Below the Curie temperature all-ferromagnetic materials show the identified hysteresis in the B (i.e. flux density) versus H (i.e. intensity of magnetic field) curves. Beginning with an unmagnetised specimen, B varies reversibly along with H for small fields. Because there is no hysteresis in that region, one classifies the initial permeability µ_r in similar way as the permeability of a paramagnetic material. As the field H is increased, B begins to enhance rapidly. Eventually approaches a saturation value B_sat. By reducing the value of H from the saturation region to zero, this is observed that there remains a flux density B_r termed as remanent flux density. Because H = 0, the material should be permanently magnetised, actually the magnetisation corresponding to Br is equivalent to B_r/µ_r. The field H_c needed to reduce the flux density to zero is termed as coercive force. The energy needed to take the material through one full cycle of magnetisation is proportional to the area enclosed through the loop.

Hysteresis Loop