Home » BASIC FUNDA » ABSOLUTE, RELATIVE PERMEABILITY

ABSOLUTE PERMEABILITY:
This is the property of a medium, on which magnetism and electromagnetism depends. In other words, the ability of the medium to conduct magnetic force is called the permeability of that medium.
Magnetic permeability is directly proportional to the conductivity of magnetic force. The permeability of a medium depends on humidity, temperature and frequency of the applied field.
The S.I unit is Henry/meter.

RELATIVE PERMEABILITY:
Vacuum or free space has chosen as reference medium for its poorest permeability of µ0=4πX10-7 Henry/meter.
The relative permeability is the ratio of the permeability of that material to the air or vacuum.
µr= µ/ µ0,
or, µ = µ0 X µr.
Now, we can write absolute permeability is the ratio of flux density to the magnetic field strength of that material and expressed as µ = B/H Henry/meter.
Or, B = µ X H Weber/m2.
= µ0 µrH wb/m2.
= µ0H wb/m2 in air.
In vacuum, B00H,
Again, B=µrµ0H,
B=µrB0,
µr = B(material)/B0(vacuum).
So, relative permeability is the ratio of flux density of material to the flux density of vacuum.

When the value of µr is less than 1, the material is called as diamagnetic material.
• When µr value is near about 1, the material is called as paramagnetic material.
• When µr value is greater than 1, we call the material as ferromagnetic material.