Definition of Magnetic Permeability
Magnetic permeability is the ability of a material to respond to how much electromagnetic flux it can support to pass through itself within an applied electromagnetic field.
In other word magnetic permeability of a material is the degree of magnetization capability.
Notation of Magnetic Permeability
Magnetic permeability is expressed in μ that is a Greek Letter. In 1885, Mathematician Oliver Heaviside had termed magnetic permeability as μ.
How to find out Permeability of any Material or Medium
In electromagnetism, H is known as the magnetizing force that signifies the ability of magnetic dipole organizations in any material or medium by magnetic field density B. The relation between B and H is directly proportional, i.e. B α H.
Or, B = μH, where, μ is the proportional constant of that material or medium and it is termed as magnetic permeability.
Hence we can write,
So, in other word magnetic permeability is defined as the ratio of magnetic flux density (B) of a material to its electro-magnetizing force (H).
Unit of Electromagnetic Permeability
The unit of Electromagnetic Permeability is Henry/meter or Newton/sq-ampere.
Permeability in Free Space
Permeability in free pace is denoted as μ0. Its value is 4ᴫ × 10-7 H/m. This value of permeability is taken as standard value that is treated as permeability constant.
Permeability of another Medium or Substance
Permeability of another medium or substance is denoted as μ only. Relative permeability is the ratio of permeability of any substance to that of free space and it is denoted as μr, i.e.
So, permeability of any medium or material is
Factors Effecting on Permeability
As permeability of any material depends on several factors:
- Position in the medium
- Frequency of the applied field
Classification of Materials as per Permeability
Diamagnetic: μr is less than 1, this material has opposition to external magnetic field.
Paramagnetic: μr is near about 1 but not exactly 1, this material is weakly attracted by external magnetic field.
Ferromagnetic: μr is greater than 1, this material is strongly attracted by external magnetic field.
What is Complex form of Permeability?
Complex permeability comes into account for high frequency magnetic field effects. A phase lag is created between H and B.