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Re: [Phys-L] big circuit

On 2021/Nov/24, at 20:47, John Denker via Phys-l <> wrote:

The Pointing vector is neither necessary nor sufficient for
answering the questions posed by the video. You can perfectly
well figure out how the "big circuit" works using a lumped LC
model, which is vastly more appropriate to the introductory
physics course. So the Poynting vector is less important to
this circuit than the staircase was to the Three Stooges.

I think I’ve lost too many marbles, as the below may not be apropos. (At least I started W/many.)

I made a lumped transmission line using UPS transformers and giant caps. I wanted to show a macro delay line whose total delay was on the order of a few seconds. Unfortunately, it’s Q is so low that it’s only slightly convincing. I used an old Vernier interface, because it has four analog inputs. Thereby one can see the difference between an open, matched, and shorted end. At some point (if I live long enough) I’ll remake it by purchasing better inductors and non-electrolytics (if possible). However, I had (given away at the recent NCN section AAPT meeting), an old 500 MHz bandwidth ’scope, and many several meters long thin net cables. My sig. gen. is barely adequate (I kept it.)

One may view the results here: <>

I suggest viewing the thin net file, the co-ax data text, and the cable connections. The other pics are unintelligible.

Unfortunately, I never measured the co-ax. lengths

I kept the RG 62/U lengths (4X ~five meters) because of their MHV connectors. I don’t remember if the ’scope revealed the connector lumps. I read type N connectors are better.

At one point I either increased the pulse rep. rate or used a sine gen. to resonate the line. (Must try that W/the macro line!)

bc …. has become a rather poor experimentalist.

p.s. I discovered I’d put (again not index p. linked) delay line articles. Here: <>