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denis
Posted: Sun Feb 04, 2007 10:21 pm
Guest
I am concern about my understanding of the inductance formula of a
coax cable which is

L = u0 * l /(2*pi) * ln(b/a)

u0 is the permittivity,
b is the outter radius
a is the inner radius

What is the physical meaning of the term 1/a when a come near 0?
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Don Kelly
Posted: Mon Feb 05, 2007 12:28 am
Guest
"denis" <denisl@sysacom.ca> wrote in message
news:1170642062.369281.199090@q2g2000cwa.googlegroups.com...
Quote:
I am concern about my understanding of the inductance formula of a
coax cable which is

L = u0 * l /(2*pi) * ln(b/a)

u0 is the permittivity,
b is the outter radius
a is the inner radius

What is the physical meaning of the term 1/a when a come near 0?

The meaning is that it blows up mathematically. In addition it implies that
the flux density at radius 1/a also blows up. The model is good only for
conductors with a radius greater than 0 -which fits all known circular
conductors. The formula does seem to imply all current on the surface of the
conductor which is not true for low frequencies and a correction is used
(gemetric mean radius).

Don Kelly dhky@shawcross.ca
remove the X to answer
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