Hysteresis

3 key takeaways

• Hysteresis occurs when the effects of a force or influence on a system persist after the force is removed, causing a lagged response.
• It is observed in various fields, including physics, economics, and engineering, and is often associated with systems that have memory or history-dependent behavior.
• Understanding hysteresis can help in predicting the long-term behavior of systems and in designing interventions to mitigate its effects.

What is hysteresis?

Hysteresis is a term used to describe systems where the current state depends not only on present conditions but also on past states and inputs. This dependency on history means that the system may exhibit different behaviors when subjected to the same conditions at different times, depending on its past experiences. Hysteresis can lead to a situation where the system does not return to its original state immediately after the influencing force is removed.

The concept of hysteresis is applicable in various domains:

Physics: In magnetism, hysteresis refers to the lag between changes in the magnetizing force and the resulting changes in magnetization. Even after the external magnetic field is removed, some magnetization remains, which is known as remanent magnetization.

Economics: Hysteresis in economics can refer to the persistence of economic effects after the initial causes have been removed. For example, high unemployment rates may persist even after the factors causing the initial rise in unemployment have been addressed, due to long-term impacts on workers’ skills and employability.

Engineering: In materials science, hysteresis describes the lag between applied stress and strain in materials like rubber or metals, where the deformation response depends on the material’s loading history.

Examples of hysteresis

Magnetic Hysteresis: When a ferromagnetic material is exposed to a magnetic field, its magnetization increases. If the magnetic field is then reduced to zero, the material retains some magnetization instead of returning to a non-magnetized state. This lag in response creates a loop when plotting magnetization versus magnetic field strength.

Economic Hysteresis: During a recession, high unemployment can persist even after the economy begins to recover. This persistence can occur because long-term unemployment may erode workers’ skills and reduce their chances of re-entering the workforce quickly, leading to a slow recovery in employment levels.

Elastic Hysteresis: In materials like rubber, when the material is stretched and then released, it does not immediately return to its original shape. The stress-strain relationship forms a hysteresis loop, indicating energy loss in the form of heat during the loading and unloading cycles.

Implications of hysteresis

Hysteresis has significant implications across various fields:

Memory Effect: Systems exhibiting hysteresis have a memory of past states, which can affect their future behavior. This characteristic is crucial in designing materials and devices that rely on predictable performance under varying conditions.

Delayed Recovery: In economics, hysteresis can explain why economies or labor markets take a long time to recover from shocks. Understanding hysteresis can help policymakers design better interventions to address long-term unemployment and other persistent economic issues.

Energy Loss: In materials science, hysteresis is associated with energy dissipation. For instance, the hysteresis loop in rubber indicates energy loss as heat during cyclic loading, which is important in applications like tire design.

Predictive Modeling: Recognizing hysteresis effects is essential for developing accurate models in various scientific and engineering disciplines. These models can predict how systems will respond to changes based on their history, leading to better planning and optimization.

Related topics

• Magnetic hysteresis
• Economic hysteresis
• Elastic hysteresis
• Lagged response in systems

Explore these related topics to gain a deeper understanding of how hysteresis manifests in different contexts and its implications for various scientific and practical applications.