Remanenz

Remanenz is a term used in physics, particularly in magnetism, to describe the residual magnetism that remains in a ferromagnetic material after the external magnetic field has been removed. When a ferromagnetic material is exposed to a magnetic field, its magnetic domains align with the field, causing it to become magnetized. Upon removal of the external field, not all of these aligned domains return to their random state. Some of the alignment persists, resulting in a net magnetic moment within the material. This persistent magnetism is known as remanence.

The strength of the remanent magnetization is a material property and depends on the type of ferromagnetic material. Materials with high remanence are often used in permanent magnets, as they retain a strong magnetic field without continuous external energy input. Conversely, materials with low remanence are preferred in applications where the magnetic field needs to be easily switched on and off, such as in transformer cores or read/write heads for magnetic storage.

The concept of remanence is closely related to the hysteresis loop of a ferromagnetic material, which graphically represents the relationship between the applied magnetic field and the resulting magnetization. The point where the hysteresis loop crosses the magnetization axis (when the applied field is zero) indicates the remanent magnetization. This property is crucial for understanding and designing magnetic devices.