Magnetic coercivity and relative permeability

This means that the coercive flux would also be four times higher than if the material was surrounded by air. In summary, when looking at a hysteresis loop, the x-axis represents the magnitude of H-field and the y-axis represents the magnitude of B-field. H is measured in units of electricity and B is measured in units of magnetic flux density. When calculating coercivity, it is important to consider the relative permeability of the material being magnetized. In this case, with Alnico having a relative permeability of 4 and air having a relative permeability of 1, the coercive flux would be four times higher when the Alnico block is surrounded by air.
  • #1
anorred
59
0
So when looking at a hysteresis loop, the x-axis is the magnitude of H-field, and the y-axis is the magnitude of B-field. H is in units of electricity and B is in units of magnetic flux density.

My question relates to how coercivity is determined if the material being magnetized has a relative permeability greater than one.

Alnico has a relative permeability of 4, and air has a relative permeability of 1. If you're trying to calculate the magnetic flux required to demagnetize the Alnico block, you can use B=uH. If the alnico block is surrounded by air, would you use u=1 or u=4 to find the coercive flux?
 
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  • #2
In this case, you would use the relative permeability of the material being magnetized (in this case, 4), so B=4H.
 

1. What is magnetic coercivity?

Magnetic coercivity is the measure of the resistance of a magnetic material to becoming demagnetized. In other words, it is the ability of a material to maintain its magnetization in the presence of an external magnetic field. The higher the coercivity, the more difficult it is to demagnetize the material.

2. How is magnetic coercivity measured?

Magnetic coercivity is typically measured in units of Oersted (Oe) or Ampere/meter (A/m). This is done by applying an increasing external magnetic field to the material until its magnetization is reduced to zero. The strength of the applied field at this point is the coercivity of the material.

3. What is relative permeability?

Relative permeability is the measure of how easily a material can be magnetized in the presence of an external magnetic field. It is the ratio of the material's magnetic permeability to the magnetic permeability of free space. A material with a high relative permeability will be more easily magnetized than a material with a low relative permeability.

4. How does magnetic coercivity affect the performance of magnetic materials?

The higher the coercivity of a material, the more stable its magnetization will be, making it ideal for applications where a strong and consistent magnetic field is required. For example, materials with high coercivity are commonly used in permanent magnets for electric motors, generators, and other industrial applications.

5. Can magnetic coercivity and relative permeability be changed?

Yes, both magnetic coercivity and relative permeability can be changed through various methods such as heat treatment, mechanical stress, and adding alloying elements. These techniques can be used to optimize the magnetic properties of a material for a specific application.

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