EMI
(Electromagnetic Interference) 
A
useful definition of EMI noise is any signigicant signal energy that
causes unintended, undesirable circuit function or inadequate EMC
performance. 

AC
Initial Permeability (£giac) 
This
is the limit value of magnetic core permeability at the origin of
the virgin magnetization curve. It's given by the following formula: 


Inductance
(L): 
The
magnetic flux linkages in Maxwellsturns per ampere of magnetizing
current. 


Inductance
Factor (AL) 
Inductance
factor is defined as the self inductance per unit turn of a coil of
a given shape and dimension wound on a magnetic core, and is determined
by the following formula: 


Quality
Factor (Q): 
The
efficiency of an inductor, that is the ratio of series inductive reactance
to loss resistance. 


Loss
factor (tan£_): 
Deviation
from ideal phase angle (90°)
due to losses. 



Relative
Loss Factor (tan£_
/£giac) 
Losses
per unit of permeability. Figure merit of a material. 


Curie
Temperature (Tc): 
emperature
at which a ferromagnetic material loses its ferromagnetism and becomes
paramagnetic(£g
approaches 1) 


Relative
Temperature Coefficient of lnitial permeability
(£\£gr):

This
is the value obtained by dividing the temperature coefficient of the
initial permeability(£\£g)
by the initial permeability. 


Specific
Gravity (d) 
It's
calculated from its volume and weight, as shown below: 

