Glossary

Symbol	Definition	Units
A_e	Effective Cross-Sectional Area - In a structure containing a non-uniform 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.	mm²
_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 N²•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/T²
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 Amp-Turns/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 Amp-Turns/cm
L	Inductance - The magnetic flux linkage in Maxwell-turns 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.	^ºC
µ	Permeability - The ratio of magnetic flux density in gauss to magnetic field strength in oersteds. 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.	mm³
W_aA_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.	cm⁴