May I first wish you and your family a Happy Xmas. Father Christmas and the grandchildren visited us yesterday so I'm free today to think ...
I'll come back on absorbtion rates when I've finished a few observations here, but in the meantime could I again ask for your opinion on two schoolboy...
Hello
If I blow air containing a fixed kg/m3 of water vapour over anhydrous CaCl2, will the absorbtion rate change if the air temp is different? To simplify, we neglect exotheric heat generated by hygroscopy.
Thanks for your answers to this rather simple question.
Hi
No, resistance is a very good indicator of shallow water depth variations but I'm not sure you can calculate exactly the depth because the voltage/current may not be linear. I'm still working on this possible non-linearity.
Firstly I'm awaiting a precise AC signal source which should counter...
Now the real challenge would be to deduce by scientific reasoning why simple tap water is linear at these voltages ranges and wouldn't be at other temperatures/concentrations/voltages, if that is the case, Beyond me, friends!
Hi
There was an elementary shame-on-you experimental error. My 50 Hz AC supply was a simple "about" 10V output mains transformer whose voltage fell off when I pulled current. Temperature variation imprecision too. I dug out my signal generator, checked it on the oscillo' and started again...
Hi everbody
My plots seem to show that conductivity between two nails immersed a few mm in tap water falls off at low voltages instead of being a horizontal flat line as would be the case for a linear ohmic medium. And the deeper the immersion, the less linear the conductivity. Is this normal...
Hi
Back in 2011 here https://www.physicsforums.com/threads/resistance-between-two-points-in-an-infinite-volume-of-resistive-gas.513388/ the question of the resistance between two points in an infinite volume of resistive gas was raised but petered out without a solution.
The solution could be...
Hi
I have the complete solution to this problem in the enclosed image. It comes from a book on thermal conductivity, so replace "source" and "drain" by .electrodes, and "isotherm" by "equipotential line". I've re-written it with S the half-distance between the electrodes and r0 their radius to...
Hi
I have a result for this problem. :
We can see that as the electrodes become further apart, the non-straight paths to the opposite electrode become "worthwhile".
The Shape factor formula is quoted in thermal conductiviy documents as the Shape Factor for heat conduction between two tubes...
In total agreement fo the No, that was the gist of my previous message, that I started talking about ellipses and nobody corrected me. I discovered my error going closely thru' the calculations in your PJ.
"The filamentary..." Could you be more explicit on these last two sentences. Thanks
I believe I was the first person to use the word ellipse, but in fact the equipotential lines in Hetsch's original image and in the document Baluncore posted are quite simply round circles. They are applicable to the electric field around two opposite current carrying parallel wires in a medium...
That's more than good enough for me, equipotential lines on an infinite surface ARE elliptic. Thanks for this major contribution.
So now I can define such a typical line with value a and any old value b, less than a of course. I now wish to define a second line, twice as far out, so 2a, having...
Jeff, graph of this image from the preceeding page :
Baluncore,
"they are all perfact circles" See image below. They are obviously not for a closed surface, what is the proof that they should they be so for an infinite surface ?
"they can be used to model the fields between cylindrical...
See Excel image. The 6 red lines are ellipses having the same two focal points. The two black ellipses pass through these two focal points. It looks very much like the red and black lines cross at 90°. So the focal points could be the point contacts, the red ellipses equipotential lines and the...
By the use of the words circle and eccentric together, are you implying that the equipotential lines are ellipses? It might help if they were, but offhand I can't see why they should follow the strict curvature imposed by a and b of ellipses.
My supposition was that, for example in this image...