Monday, November 28, 2011

Equation 13.71

Has anyone been able to figure out how equation 13.71 was derived?

1 comment:

Dragan said...

In Fig.13.29, in the step from (c) to (d), the layer is stretched by lw/l, where l is the length in (c), equal to nl*h, and h is given in (13.70). Porosity is equal to the ratio of the areas, i.e. eta = l/lw, see (13.72)

Then, to keep the same dc resistance from (c) to (d), resistivity in (d) is increased by 1/eta. Finally, since skin depth (13.69) is proportional to square-root of resistivity, effective skin depth in (13.71) is increased by by 1/square-root(eta)