The axial cylinder models is characterized by the outer
diameter,
, the inner diameter,
, length,
. The magnetic reluctance is determined by:
The area of cross section yields:
A hollow cylinder is depicted in the above figure left for
. A solid cylindric flux tube an be considered by setting the inner
radius,
, equal to zero.
A circular sector of the area of cross section with central
angle
is depicted in the above figure right.