Hysteresis¶

When ferromagnetic materials(Ferromagnetism) are placed within a coil of wire carrying an electric current, the magnetic field strength H, caused by the current, forces some or all of the atomic magnets in the material to align with the field. The net effect of this alignment is to increase the total magnetic field, or magnetic flux density B. The aligning process does not occur simultaneously or in step with the magnetizing field, but lags behind it. This lagging of the magnetization of a ferromagnetic material, such as iron, behind variations of the magnetizing field is known as Hysteresis.

1. Hysteresis | Britannica