hysteresis loop
Quick Summary
Hysteresis describes the phenomenon where the magnetization of a ferromagnetic material, like iron, lags behind changes in the magnetizing field. When a magnetic field is applied, atomic magnets within the material align, increasing the overall magnetic field. However, this alignment doesn't happen instantly; it lags behind the applied field.1
As the magnetizing field increases, the magnetic flux density reaches a saturation point. When the field decreases, the flux density drops but retains some magnetism, known as remanence. To reduce the flux density to zero, a reverse magnetic field, called the coercive force, is needed. Continuing this cycle creates a loop on a graph, called a hysteresis loop, which represents the lagging effect. The energy lost as heat during this process is called hysteresis loss and is proportional to the area of the loop. Materials with narrow hysteresis loops are preferred for transformer cores to minimize energy loss.12
Ask Britannica AI about this topic
Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.
