Re: Can twisted wire replace shielded wire?

On 2005-11-29, Keith Williams <krw@xxxxxxxxxx> wrote:
> In article <3v2ln9F13vjq4U2@xxxxxxxxxxxxxx>, boblatest@xxxxxxxxx
> says...
>> ["Followup-To:" header set to sci.electronics.design.]
>> On Mon, 28 Nov 2005 14:40:12 -0500,
>> Keith Williams <krw@xxxxxxxxxx> wrote
>> in Msg. <MPG.1df5272515469f3c9896d5@xxxxxxxxxxxxxxxxxxx>
>>
>> > A zero-resistance (ideal) transmission line is just as realizable
>> > as an infinite one.
>>
>> Superconductivity goes a pretty long way towards zero resistance. Wind a
>> superconducting transmission line once around the equator and make your
>> measurement on one end (leave the other end coming through your lab's
>> back door alone). Then you have roughly 1/4 second to establish your DC
>> resistance.
>
> Ok, but 24K miles isn't very close to infinite. ;-) A one foot
> copper t-line looks like a pretty good resistor for a 2E-9 seconds
> or so. ...and not too much further from "ideal" or "infinite". ;-)

24K miles is as close to infinite length as 0.25 seconds of
steady current is to DC.

robert
.

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