I read in sci.electronics.design that Mattias <
[email protected]>
It will, if you actually do the experiment.
I think you have been confused by poor explanations. A cable works only
like a plain RC at low frequencies. The conductors have *inductance* as
well as resistance, and at a sufficiently high frequency, this prevents
the apparent RC low-pass filter actually existing.
There isn't any 'standard capacitance for coaxial cable'. Cables of
different dimensions and dielectrics have widely different capacitances
per unit length.
I think this is just more confusion. The cable is about 900 m long, and
in free space a wavelength of 900 m belongs to a frequency of 333 kHz.
But the wave travels more slowly in the cable, by a 'velocity factor'
factor of around 1.6 normally, so the cable is a wavelength long at
about 208 kHz. It looks to me as though your teacher has neglected the
velocity factor (or has assumed a coaxial cable with vacuum dielectric!)
and thinks that the cable is half a wavelength long at 115 kHz. Not that
being half a wavelength long has any significant consequences if you are
feeding the signal into the cable correctly.
--
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http://www.jmwa.demon.co.uk
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