Describe the concept of hysteresis in magnetic materials.
1 Answer
Hysteresis is a phenomenon observed in magnetic materials that describes their ability to retain magnetization even after the applied magnetic field has been removed. In other words, it is the lagging of the magnetic response behind the changes in the external magnetic field.
When an external magnetic field is applied to a magnetic material, the atomic or molecular magnetic moments within the material align themselves with the direction of the external field. This alignment creates a net magnetization in the material, meaning it becomes magnetized.
Now, when the external magnetic field is gradually reduced back to zero, the atomic or molecular magnetic moments do not instantly return to their initial random orientations. Instead, they maintain some degree of alignment, leading to a residual magnetization. This phenomenon is known as remanence or the magnetic remanent moment.
To completely demagnetize the material, an external magnetic field of the opposite direction must be applied. This new field will gradually reduce the residual magnetization to zero, at which point the material is considered demagnetized.
If we plot the relationship between the external magnetic field (H) and the resulting magnetization (M) in a graph, we get a loop called the hysteresis loop. This loop shows the magnetization behavior during the magnetization and demagnetization processes.
The area inside the hysteresis loop represents the energy losses in the material due to the realignment of magnetic domains during the magnetization process. These energy losses result in heat dissipation, making hysteresis an essential consideration in various applications, such as transformers and electric motors.
Different magnetic materials have different hysteresis characteristics, and the shape of the hysteresis loop can vary depending on the composition and structure of the material. Soft magnetic materials, used in applications like transformers, exhibit small hysteresis loops with low energy losses, while hard magnetic materials, used in permanent magnets, have larger hysteresis loops with higher energy losses.
When an external magnetic field is applied to a magnetic material, the atomic or molecular magnetic moments within the material align themselves with the direction of the external field. This alignment creates a net magnetization in the material, meaning it becomes magnetized.
Now, when the external magnetic field is gradually reduced back to zero, the atomic or molecular magnetic moments do not instantly return to their initial random orientations. Instead, they maintain some degree of alignment, leading to a residual magnetization. This phenomenon is known as remanence or the magnetic remanent moment.
To completely demagnetize the material, an external magnetic field of the opposite direction must be applied. This new field will gradually reduce the residual magnetization to zero, at which point the material is considered demagnetized.
If we plot the relationship between the external magnetic field (H) and the resulting magnetization (M) in a graph, we get a loop called the hysteresis loop. This loop shows the magnetization behavior during the magnetization and demagnetization processes.
The area inside the hysteresis loop represents the energy losses in the material due to the realignment of magnetic domains during the magnetization process. These energy losses result in heat dissipation, making hysteresis an essential consideration in various applications, such as transformers and electric motors.
Different magnetic materials have different hysteresis characteristics, and the shape of the hysteresis loop can vary depending on the composition and structure of the material. Soft magnetic materials, used in applications like transformers, exhibit small hysteresis loops with low energy losses, while hard magnetic materials, used in permanent magnets, have larger hysteresis loops with higher energy losses.