Hysteresis

Definition

Hysteresis is the lag between the input and output of a system, often observed in magnetic materials and certain mechanical systems, where the effect of an external force is not immediately reversed when the force is removed. This phenomenon can be seen in how materials respond to changing magnetic fields, leading to a looped graph that shows how magnetization changes with applied magnetic field strength. Hysteresis highlights the importance of energy loss, which is relevant in understanding eddy currents and their implications in electrical applications.

5 Must Know Facts For Your Next Test

1. Hysteresis is commonly represented by a loop on a graph where the output does not follow the same path back when the input is reversed, indicating energy loss.
2. In magnetic materials, hysteresis can result in residual magnetism, meaning materials can retain some magnetization even after an external magnetic field is removed.
3. Eddy currents are directly related to hysteresis as both involve the interaction of changing magnetic fields with conductive materials, leading to energy dissipation.
4. Materials with low hysteresis losses are preferred in applications like transformers and electric motors to improve efficiency.
5. The area within a hysteresis loop on a graph represents the energy lost per cycle due to internal friction and other factors.

Review Questions

• How does hysteresis relate to the behavior of magnetic materials when exposed to alternating magnetic fields?
  • Hysteresis is critical in understanding how magnetic materials react to alternating magnetic fields. When these materials are subjected to a changing magnetic field, their magnetization does not instantly follow the changes due to hysteresis. This results in a lag, forming a loop on a graph that illustrates how the magnetization decreases when the field is removed. This behavior is essential for applications like transformers, where energy efficiency depends on minimizing hysteresis losses.
• Discuss how hysteresis impacts the design and efficiency of electrical devices that utilize eddy currents.
  • Hysteresis significantly affects the design and efficiency of electrical devices that utilize eddy currents, such as transformers and induction cooktops. The presence of hysteresis leads to energy losses represented by the area within the hysteresis loop on a graph. Engineers aim to use materials with low hysteresis loss in these devices to reduce wasted energy and improve overall efficiency. Thus, understanding hysteresis is crucial for optimizing the performance of devices where eddy currents are present.
• Evaluate how understanding hysteresis can lead to advancements in material science and electrical engineering.
  • A deep understanding of hysteresis can drive advancements in material science and electrical engineering by informing the development of new materials with improved properties. By focusing on reducing hysteresis losses, engineers can create more efficient devices, such as electric motors and transformers, ultimately saving energy and reducing costs. Additionally, insights into hysteresis behavior can lead to innovations in applications ranging from data storage technologies to renewable energy systems, making it a vital concept for future technological progress.

Related terms

Magnetic Hysteresis: The behavior of magnetic materials that shows a lag in magnetization compared to the applied magnetic field, forming a hysteresis loop.

Eddy Currents: Circular currents induced in conductors when exposed to changing magnetic fields, often causing energy loss due to resistance.

Energy Loss: The loss of energy that occurs in systems like magnetic materials and conductors due to effects like hysteresis and eddy currents.