What is Magnetic Hysteresis?
Magnetic hysteresis is a phenomenon that occurs in ferromagnetic materials, such as iron, when an external magnetic field is applied. When a magnetic field is applied to a ferromagnet, the atomic dipoles align themselves with the field, causing the material to become magnetized. This magnetization is retained even when the external magnetic field is removed.
History and Background
The concept of magnetic hysteresis has been understood for centuries, but the term itself was first coined in the 19th century. Ferromagnetic materials have been used for various purposes, including magnetization of compass needles and other objects. The study of magnetic properties has been a long-standing area of research in physics and materials science.
Key Facts and Principles
- Magnetic hysteresis occurs in ferromagnetic materials, such as iron, when an external magnetic field is applied.
- The relationship between the external magnetic field (H) and the magnetization (M) of the material is not linear.
- When a magnetic field is applied and then removed, part of the alignment of the atomic dipoles is retained, causing the material to become magnetized.
- To demagnetize a ferromagnetic material, it requires heat or an external magnetic field in the opposite direction.
- The width of the middle section of the hysteresis loop is twice the coercivity of the material.
The Hysteresis Loop
The relationship between the external magnetic field (H) and the magnetization (M) of a ferromagnetic material is plotted in a graph called the hysteresis loop. The hysteresis loop has a main loop and a series of small, random jumps in magnetization called Barkhausen jumps.
Barkhausen Jumps
Barkhausen jumps are small, random changes in magnetization that occur in ferromagnetic materials. These jumps are due to crystallographic defects, such as dislocations, in the material.
Magnetic Hysteresis in Other Materials
Magnetic hysteresis is not exclusive to ferromagnetic materials. Other magnetic orderings, such as spin glass ordering, also exhibit this phenomenon.
Examples and Applications
Magnetic hysteresis is used in various applications, including:
- Hard disk drives, which rely on the element of memory provided by magnetic hysteresis.
- Magnetic resonance imaging (MRI) machines, which use the magnetic properties of ferromagnetic materials to produce detailed images of the body.
- Magnetic sensors, which use the magnetic properties of ferromagnetic materials to detect changes in the magnetic field.
Relation to Apiary Mission
While magnetic hysteresis is not directly related to the Apiary mission, it is an important area of research in materials science and physics. Understanding the properties of ferromagnetic materials can lead to advancements in various fields, including energy storage and conversion, medicine, and technology.
FAQ
What causes magnetic hysteresis? Magnetic hysteresis is caused by the alignment of atomic dipoles in a ferromagnetic material when an external magnetic field is applied.
How is magnetic hysteresis measured? Magnetic hysteresis is measured by plotting the relationship between the external magnetic field (H) and the magnetization (M) of the material in a graph called the hysteresis loop.
What is the difference between ferromagnetic and spin glass ordering? Ferromagnetic ordering refers to the alignment of atomic dipoles in a material in response to an external magnetic field, while spin glass ordering refers to the random arrangement of magnetic moments in a material.
What is the significance of Barkhausen jumps in magnetic hysteresis? Barkhausen jumps are small, random changes in magnetization that occur in ferromagnetic materials due to crystallographic defects. They are significant because they can affect the magnetic properties of the material.
How is magnetic hysteresis related to the Apiary mission? Magnetic hysteresis is not directly related to the Apiary mission, but it is an important area of research in materials science and physics that can lead to advancements in various fields.