A_{e} 
Effective CrossSectional Area  In a structure containing a nonuniform cross section, the effective magnetic cross section is the area of a structure with uniform cross section which is equivalent to the first for purposes of magnetic calculations. Also called Ac. 
mm^{2} 
_{AL} 
Inductance Factor  Industry standard method of expressing the inductance of a magnetic core, independent of turns. The inductance (in µH) of a coil with N turns wound on a core with known A_{L} is N^{2}•A_{L}/1000. A_{L} is established at low flux density (<1mT) and at a low enough frequency to avoid error from resonance or frequency response. 
mH/1000T
or
nH/T^{2} 
awg 
American Wire Gauge  also known as the Brown & Sharpe wire gauge, is a standardized wire gauge system 

B 
Magnetic Flux Density  The number of lines of magnetic force per square centimeter of material. Also called Induction or Magnetic Induction. 
Gauss
Tesla 
BH Curve 
BH Curve  Relation between magnetic induction B and magnetizing force H for a magnetic material. Also called Magnetization Curve or Hysteresis Loop. 

B_{r} 
Remanence  The residual flux level in a core at H = 0. The measured B_{r} depends on the recent magnetization history of the core. B_{r}/B_{max} is thesquareness. 
Gauss
Tesla 
B_{max} 
Saturation Flux Density  The maximum flux density a magnetic material can accommodate. At B_{max}, further increases in H result in no significant increase in B 
Gauss
Tesla 
H 
Field Strength  The externally applied magnetic field. Also called Magnetizing Force or mmf(Magnetomotive Force.) 
Oersted
AmpTurns/cm 
H_{C} 
Coercive Force  The reverse magnetic field needed to reduce a previously magnetically saturated core from B=B_{r} to B=0. H_{c} is a measure of the width of the hysteresis loop at low frequency. 
Oersted
AmpTurns/cm 
L 
Inductance  The magnetic flux linkage in Maxwellturns per ampere of magnetizing current. 
Henries 
l_{e} 
Magnetic Path Length  The effective length along which field strength is applied for a particular core shape and dimension. 

T_{C} 
Curie Temperature  Temperature at which a ferromagnetic material loses its ferromagnetism and becomes paramagnetic (μ_{e} approaches 1). For ferrites, the effects of exceeding Curie temperature are fully reversible. 
^{º}C 
µ 
Permeability  The ratio of magnetic flux density in gauss to magnetic field strength inoersteds.
μ= β/H


μ_{e} 
Effective Permeability  If a magnetic circuit is not homogeneous (i.e., contains an air gap), the effective permeability is the permeability of a hypothetical homogeneous (ungapped) structure of the same shape and dimensions that would give an inductance equal to the gapped structure. 

V_{e} 
Effective Magnetic Volume  Product of A_{e} and l_{e}. 
mm^{3} 
W_{a}A_{c} 
Area Product  Product of winding window area and A_{e}. Also called A_{p}. Area product is a useful parameter for estimating the power handling capability of a core, if the frequency and circuit topology are known. 
cm^{4} 