Magnetic hysteresis

Definition

Magnetic hysteresis refers to the lag between the magnetization of a material and the applied magnetic field. This phenomenon occurs when a magnetic material is magnetized and then demagnetized, exhibiting a relationship that forms a loop on a graph of magnetic field strength versus magnetic flux density. This loop indicates how the material retains some magnetization even after the external field is removed, demonstrating its magnetic memory.

5 Must Know Facts For Your Next Test

1. The area enclosed within the hysteresis loop represents energy loss during magnetization and demagnetization, which is important for applications like transformers and electric motors.
2. Materials with large hysteresis loops are often referred to as hard magnets, while those with small loops are called soft magnets.
3. The shape of the hysteresis loop can provide insight into the magnetic properties of materials, including their remanent magnetization and coercivity.
4. Hysteresis can affect the efficiency of devices that rely on changing magnetic fields, leading to heat generation due to energy losses.
5. Temperature can influence hysteresis behavior; as temperature increases, the coercivity and remanence of many materials typically decrease.

Review Questions

• How does magnetic hysteresis relate to magnetic susceptibility in materials?
  • Magnetic hysteresis and magnetic susceptibility are interconnected as both describe how materials respond to applied magnetic fields. Magnetic susceptibility indicates how easily a material can be magnetized, while hysteresis highlights the lag in response when the external field changes. The degree of hysteresis exhibited by a material can affect its susceptibility; materials with high hysteresis may have lower effective susceptibility due to energy losses associated with their retained magnetization.
• Discuss the significance of remanence and coercivity in understanding magnetic hysteresis.
  • Remanence and coercivity are key aspects of magnetic hysteresis that help in understanding a material's performance in practical applications. Remanence indicates how much magnetization remains after an external field is removed, while coercivity measures how resistant a material is to demagnetization. Together, these properties determine how suitable a material is for specific applications like permanent magnets or soft magnetic cores, influencing decisions in engineering and technology.
• Evaluate how temperature variations affect magnetic hysteresis and its implications for technological applications.
  • Temperature variations significantly impact magnetic hysteresis by altering both coercivity and remanent magnetization. As temperature rises, many materials exhibit decreased coercivity, making them easier to demagnetize, which can lead to reduced efficiency in devices such as transformers. Understanding this relationship helps engineers design systems that maintain performance under varying thermal conditions, ensuring reliability in applications ranging from electrical engineering to data storage technologies.

Related terms

Magnetic susceptibility: Magnetic susceptibility is a measure of how much a material will become magnetized in an external magnetic field, reflecting its ability to be magnetized.

Remanence: Remanence is the residual magnetization that remains in a magnetic material after an external magnetic field has been removed.

Coercivity: Coercivity is the measure of the resistance of a ferromagnetic material to becoming demagnetized, quantifying the strength of the external magnetic field required to reduce the magnetization to zero.