Re: God dwells in a light that no man can approach unto!

Gareth McCaughan wrote:

Sam Wilson wrote:

In article <469B7129.64A0117E@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Frederick Williams <"Frederick
Williams"@antispamhotmail.co.uk.invalid> wrote:

michaeld wrote:

Of course the _signal speed_ of electricity in a wire is much higher -
normally about 1/3-2/3 of the speed of light.

Could one measure that using, say, such apparatus as one might find in a
school physics laboratory?

Ummm, let's see. Light travels in vacuum at 3x10^8 ms^-1 (300 million
metres per second). It'll travel 3 metres in 10^-8 seconds. If you've
got a significant length of cable and an oscilloscope that can work in
nanoseconds (10^-9 seconds) or GHz - not that unusual for a good 'scope
- then you should be able to do it with ease.

You might have to be careful about distinguishing between
propagation delay and other effects resulting from (e.g.)
capacitance or inductance. But: yes.

I'm finking... Suppose I take a length L of coax and put an rf signal
of frequency f in at one end, and I put a high-impedance voltmeter at
the other. I'm hoping to get standing waves in the coax, and for
certain L and f to see zero on the voltmeter. So L will equal an
integral number of quarter-wavelengths, wavelength = 4L/n, say. So the
the velocity of the standing waves is 4Lf/n. Trouble is I don't know
what n is. What I need is an exposed conductor that I can slide my
voltmeter up and down. Ooh er missus. Fun, innit?

--
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"He that giveth to the poor lendeth to the Lord, and shall be repaid,"
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Relevant Pages

  • Re: God dwells in a light that no man can approach unto!
    ... Frederick Williams <"Frederick ... Suppose I take a length L of coax and put an rf signal ... certain L and f to see zero on the voltmeter. ... the velocity of the standing waves is 4Lf/n. ...
    (uk.religion.christian)
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    ... On 27 Aug, 14:07, Frederick Williams <"Frederick ... Not a multicultural youth and community centre? ... "He that giveth to the poor lendeth to the Lord, and shall be repaid," ... as multi cultural as the community is. ...
    (uk.religion.christian)
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    ... On Oct 16, 2:16?pm, Frederick Williams <"Frederick ... [John Jones] ... If by counting you mean the human ... "He that giveth to the poor lendeth to the Lord, and shall be repaid," ...
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