Energy Loss

[anatech]

Hey poobah!,

just need some TIME is all

I said that already!

-Chris

[poobah]

[jneutron]

Originally posted by poobah
This method looks at the before and after, but not the "during".

It is only "during" that energy can be lost..so, that has to be it..the alternative, is that energy is lost arbitrarily during the transfer via series resistance and the flash energy. Arbitrary loss will not produce the half voltage result obtained which is consistent with charge conservation.

Originally posted by poobah

You of all people should have the superconductors, perfect switches, and scopes with 0 seconds/grat sweep speeds to analyze all this... do it at lunch... will you?

I had considered it, but there are some details that need to be worked out.

1. The flat plate capacitors have to be superconducting. They have to be of sufficient current capacity that a quench does not occur during the transfer.

2. An inductor must be used to limit the possibility of quenches. The inductor must be toroidal, as external fields will couple to the environment.

3. A superconducting shield around the system is needed to prevent external transmission. This raises an additional problem, which is persistent currents. This will require raising the temperature slowly after the experiment, to measure the helium heat rise when the persistent currents quench out. Note that this problem will also affect the toroid.

4. With an ideal inductor and two ideal capacitors, the oscillation will proceed unhindered forever. The only entity which will slow it down would be eddy currents in the surrounding volume.

5. The capacitor will have to be rather large to provide any reasonable capacity..Liquid helium dielectric constant is not very high, and other materials are not well characterized at that temperature.

6. Current temperature sensors are only capable of a millikelvin or so of resolution, so the heat capacity of the helium may render temperature rise measurements of persistent current energy below the system resolution.

7. Silicon switches are very odd in liquid helium...Regular PN junctions have forward voltage drops of between 8 and 30 volts, you have to warm them to 20 kelvin or so before they begin to conduct again.

Cheers, John

Sheesh, a lot of writing involved in this chop-busting post..

[poobah]

You ain't bustin my chops. You just threw in the prerequisite L (or R) that I have been maintaining is the sucker punch in all of this.

[kvholio]

LOL, i got a pretty strong hunch it was a sucker-punch-brain-teaser when i found the exact experiment in the Dutch wikipedia.
It was under the category "anomalies in physics"

Gotta run guys. Got a worp-core breach on my hands

Klaas

[ChocoHolic]

Hi Klaas,
I cannot access wikipedia from here. ...would be glad if you could send me that wikipedia essay by mail.... Oehem... only dutch? urghs..!

[theChris]

long thread, i take it everything has come up roses?

another related, an more beleiveable form of this problem (that doens't violate the charge sharing stuff or involve infinate current) is:

charge 2 caps in parallel to 100V each.
remove both.
attache these in series.

[jneutron]

Originally posted by theChris
long thread, i take it everything has come up roses?

another related, an more beleiveable form of this problem (that doens't violate the charge sharing stuff or involve infinate current) is:

charge 2 caps in parallel to 100V each.
remove both.
attache these in series.

It is not exactly the same.

Two caps in series, 1 farad each, 10 volts.

E = 1/2 C V²

in parallel,

C = 2, V = 10, E = 1/2 *2 *100, or E = 100 joules

then, put them in series

C = 1/2, V = 20, E = 1/2 * 1/2 * 400 or E = 100 joules

No loss.

(I was thinking of this scenario also...great minds think alike, right?

Cheers, John

[SY]

But John, you know that on inspection because the charges can't move.

If you want to have fun, you can make the energy "disappear" by connecting them back-to-back.

[jneutron]

Originally posted by SY
But John, you know that on inspection because the charges can't move.

yup, I simply pointed out the conservation of energy.

It was stated that ""another related, an more beleiveable form of this problem "", I pointed out the difference.

Originally posted by SY
If you want to have fun, you can make the energy "disappear" by connecting them back-to-back.

Apparently we have different ideas of what constitutes "fun"

Cheers, John