Hysteresis

Definition

Hysteresis is the lag between an input and output in a system, often observed in magnetic materials where the magnetization lags behind the applied magnetic field. This phenomenon results in a looped curve when plotting magnetization against the magnetic field strength.

5 Must Know Facts For Your Next Test

1. Hysteresis loops illustrate the energy loss due to internal friction within magnetic materials.
2. The area inside a hysteresis loop represents the energy dissipated as heat during a complete cycle of magnetization.
3. Coercivity is the measure of the resistance of a ferromagnetic material to becoming demagnetized, indicated by the width of the hysteresis loop.
4. Retentivity (or remanence) indicates how much residual magnetism remains in a material after removing an external magnetic field, shown by the height of the hysteresis loop at zero field.
5. Soft magnetic materials have narrow hysteresis loops with low coercivity and are used in applications requiring rapid magnetization and demagnetization.

Review Questions

• What does the area inside a hysteresis loop represent?
• How is coercivity represented on a hysteresis loop?
• Why are soft magnetic materials preferred for applications requiring rapid changes in magnetization?

Related terms

Magnetization: The process by which a material becomes magnetized or acquires a magnetic moment.

Coercivity:

A measure of the intensity of the applied magnetic field required to reduce the magnetization of a material to zero.

Retentivity: \text{The ability of a ferromagnetic material to retain its magnetization after an external magnetic field is removed.}