Morgan
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Electrostatic tidbits
CHARGING MECHANISMS (page 45)
"Lower into an empty glass beaker two electrodes of differing materials (e.g. gold and magnesium) and connect an electro-meter across the two
electrodes. When a suitable radio-active source (e.g. Po 210, 500 Cu) is placed at the bottom of the beaker, a potential of 1.2 volts will be
registered between the electrodes, magnesium being negative with respect to gold. Remove the radioactive source and fill the beaker with sufficient
water to partially immerse both electrodes. The electrometer will again register a potential of 1.2 volts and the same polarity."
"Both experiments deal with an electrochemical cell, using water for electrolyte in one case and air in the other. The fact that water contains ion
pairs makes it an electrically conducting electrolyte which is vital for an electrochemical cell. In the first case, Fig. 22a, the beaker contains air
instead of water, but the air is slightly ionized by the radioactive source, and although the number of ion pairs is relatively low, the ionized air
is electrically conducting and exhibits the same properties characteristic of an electrolyte."
"At first it was disappointing to discover that the potentials in Table 1 were not at all proportional but rather inversely proportional to the work
function potentials of the different materials in question. However, Table 1 has a very familiar appearance to the chemist; it resembles a chemical
activity series in which the electrical potentials are values related to the oxidation energies of the materials in question. To further prove the
electrochemical effect, the same materials were immersed in distilled water, two at a time. Differences of potential between the two materials were
then measured and found to be directly proportional to the respective differences between their values in Table 1."
"From the experiments and the results of Table 1 it became clear that we were dealing with an electrochemical effect and the following conclusions
were drawn: negative ions in air are formed from acidic molecules such as O2 and NO2. These molecules are electrophilic (electron seekers) and capture
free electrons produced in air by the various ionization processes. The molecular ion, with its valence slightly reduced by a captured electron, still
remains acidic and very active as an oxidizer. When the molecular ion with its piggyback electron oxidizes a surface material, negative charge is
transferred by the captured electron to the surface. As more ions reach the surface, a negative back-emf will build up, eventually repelling any
incoming ions until no more can reach the surface. Just as in the case of the drycell an electrical equilibrium potential is achieved."
(page 73)
"In the electrochemical charging mechanism convection currents simply bring natural ions of both signs in from outside and ventilate them through the
drop population of the cloud. However, negative ions which are extremely reactive attach themselves to drop surfaces at the bottom of the cloud while
the inert positive ions sieve through and are carried by the updrafts to the upper regions. The electrochemical charging mechanism, which is described
in Chapter 3, is very effective and despite criticism by Vonnegut, Moore, Griffith and Willet (see section 2.7.3) is the only process which can easily
be modelled in the laboratory."
"The diagram in Fig. 31 shows such a model constructed from two clumps of steel wool. The two sections of steel wool, one representing the bottom and
the other the top of a thunder cloud, are electrically insulated from each other. A fan blows air through the cloud model to simulate the updraft
winds inside a thunder cloud. A radioactive alpha particle source (Po 210, 500 micro Cu) near the fan feeds positive and negative ions at equal number
into the cloud model. Negative ions are immediately captured by the electrochemical process in the bottom section while the inert positive ions pass
through and reach the upper steel wool section where they stop together with the airflow. In a model the size of a large football over one hundred
volts of charge separation is readily achieved. A small neon light, connected across the cloud model, demonstrates the lightning discharge in a
realistic manner. The polonium 210 is readily available from several mail order suppliers and does not require a license."
http://www.scribd.com/doc/25953717/Atmospheric-Electrostatic...
[Edited on 24-9-2012 by Morgan]
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Morgan
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I don't think Accio's generator is going to be coming to a theater near you any time soon but it's interesting to think about. DARPA has given them a
small amount of money.
"Each component is made up of recycled aluminum tubes and has no moving parts. Water is pumped in as wind blows through, forcing a mist of tiny water
droplets out pinholes in the aluminum. The flow of water creates a charge, just as it does in thunderheads as water droplets rise and fall on wind
currents."
http://www.crainsdetroit.com/article/20101114/FREE/311149953...
There's a graphic on this page.
http://theeestory.com/posts/185384
Here's a very simple Lord Kelvin water dropper demonstration from MIT. It would be fun to make something a little more sparky.
http://www.youtube.com/watch?v=-ahWs9YTJkc#t=3m36s
Some basic tips for making better sparks.
"For example, a flashlight might use 3 volts at 1 ampere, putting out three watts of visible and IR light. 3volts/1amp equals 3 ohms. So for a
flashlight, any object with lots less than 3 ohms is a conductor, and any object with lots more than 3 ohms is an insulator. A flashlight "thinks"
that a 1K resistor is a good insulator, while a 0.01 ohm wire is a good conductor."
"For electrostatics, the numbers are quite different. A Kelvin waterdrop generator might produce 20,000volts at 1/2 microamp. Dividing this voltage by
this current gives 40,000,000,000 ohms. That's the line between insulator and conductor. Quite different than three ohms! So, if an object is to act
as an insulator, its resistance must be MUCH greater than forty billion ohms! For a Kelvin generator, a ten-megohm piece of wood will act like a very
good conductor. Is it any wonder that a bit of surface moisture can convert an insulating object into a conductor? The highest value of resistor
commonly available in catalogs is 33 megohms, and most electrostatic devices will see this device not as a resistor, but as a dead short.
http://amasci.com/emotor/stathint.html
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Morgan
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"The picture was taken with a digital video camera under bright fluorescent light. The sparks are not quite as bright as they appear in the pictures,
but they are nevertheless quite impressive to the uninitiated in electrostatics, not to mention being quite loud. These sparks are 5 1/2 inches (14cm)
long, but under optimum conditions I have made sparks as long as seven inches (18cm). I think with a little tweaking of the configuration, they might
be much longer."
http://www.coe.ufrj.br/~acmq/foster.html
Here's an example of the above and where I got the idea to try to make one myself. I set my leyden jar on a slab of copper and the solution is a mix
of magnesium sulfate and salt. I tried CPVC and the gray PVC and both seem to work better than the plain white. The length of the PVC tube is 6 feet.
Note how much crackle there is sliding the paper towel over the PVC. There was a cloth around the paper towel for insulation. With another design I
was able to make a 13 inch spark.
http://www.youtube.com/watch?v=6w_18SqA6x8
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Morgan
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I thought it funny he drinks the water after the Kelvin water dropper experiment.
http://www.youtube.com/watch?v=2sSqzLPMb4s#t=5m19s
Sir William Thompson/Lord Kelvin and his water dropper. In one variation he uses copper filings.
http://books.google.com/books?id=2lgwAAAAIAAJ&pg=PA391&a...
[Edited on 30-9-2012 by Morgan]
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Morgan
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Static discharge
http://www.youtube.com/watch?v=JywjBAxxJHE
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Morgan
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An easier to read format and larger diagrams.
Proceedings of the Royal Society, June 20, 1867
"If a tube (fig. 3) be added to the lid to prevent currents of air from circulating into the interior of the jar, the insulation may be so good that
the loss may be no more than one per cent. of the whole charge in three or four days. Two such jars may be kept permanently charged from year to year
by very slow water-dropping arrangements, a drop from each nozzle once every two or three minutes being quite sufficient."
http://zapatopi.net/kelvin/papers/on_a_self-acting_apparatus...
http://zapatopi.net/kelvin/kidsclub/answer.html
[Edited on 5-10-2012 by Morgan]
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Morgan
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Can Ball Lightning Exist in a Vacuum?
http://www.readcube.com/articles/10.1038/245095a0
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bfesser
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| Quote: | | I have been within 50 cm of ball lightning in its smooth and unerring passage through an aircraft<sup>2,5</sup>. I carried a penknife in
my trouser pocket, a steel tobacco tin in my left jacket pocket and a steel screwdriver in my right jacket pocket. |
Wow. Doesn't that just date it. In the last paragraph of the article, the author proposes "ball lightning to exist in regions of very low pressure
where it may not be recognized by the luminosity of the excited gas." I call bullshit. It wouldn't be proper lightning if it wasn't highly luminous.
 See: etymology of <a
href="http://www.etymonline.com/index.php?term=lightning" target="_blank">'lightning'</a>.
[Edited on 2/1/13 by bfesser]
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Morgan
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"Over the years lightning was thought to be a predominantly low altitude (<10 km) phenomenon with little of its energy coupling to the mesosphere
and ionosphere. As a result, recent observations relating lightning to energy dissipation at altitudes between 30 and 90 km came as a major surprise.
These phenomena, grouped under the name of high altitude lightning (HAL), include (a) Red sprites, (b) Blue jets, (c) Gamma ray bursts, (d) Radio
bursts (e) more? A diagram referring to the different phenomena and the location of their occurrence is shown in Fig 1.3."
http://fisica.ciencias.uchile.cl/alejo/thesis/node2.html#SEC...
"High speed photometer measurements show that the duration of sprites is only a few ms. Current evidence strongly suggests that sprites preferentially
occur in decaying portions of thunderstorms and are correlated with large positive cloud-to-ground lightning strokes. The optical intensity of sprite
clusters, estimated by comparison with tabulated stellar intensities, is comparable to a moderately bright auroral arc. The optical energy is roughly
10-50 kJ per event, with a corresponding optical power of 5-25 MW. Assuming that optical energy constitutes 1/1000 of the total for the event, the
energy and power are on the order of 10-100 MJ and 5-50 GW, respectively."
"If sprites are only barely detectable by the unaided human eye, in intensified television images obtained from the ground and from aircraft they
appear as dazzlingly complex structures that assume a variety of forms."
http://elf.gi.alaska.edu/#curres
https://www.google.com/search?q=high+altitude+lightning&...
[Edited on 1-2-2013 by Morgan]
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Morgan
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ELECTRO STATIC!
http://www.youtube.com/watch?v=7zp98GNsWIU#t=42s
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Morgan
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I thought this was a clever design.
Big sparks from a handheld electrophorus
http://www.youtube.com/watch?v=axgG_aSLKPM
http://www.rmax.com/wall-r-matte-plus3.asp
"One of the largest examples of an electrophorus was built in 1777 by German scientist Georg Christoph Lichtenberg.[7] It was 6 feet (2 m) in
diameter, with the metal plate raised and lowered using a pulley system. It could reportedly produce 15 inch (38 cm) sparks."
http://en.wikipedia.org/wiki/Electrophorus
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Morgan
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Having experimented with PVC and PTFE as a source of static electricity, a great winter activity, I started to wonder if there were any somewhat
common plastics containing iodine, just to see if that halogen had any beneficial or peculiar properties over the other halogenated plastics. I
happened on these few tidbits involving iodine but couldn't find any basic studies on the electrostatic properties of iodine in plastics.
Photoconductivity in pure and iodine-doped thin polyvinylchloride films
http://iopscience.iop.org/0022-3727/13/2/004/pdf/jdv13i2pL39...
Photoconductivity
"Classic examples of photoconductive materials include the conductive polymer polyvinylcarbazole,[2] used extensively in photocopying (xerography);
lead sulfide, used in infrared detection applications, such as the U.S. Sidewinder and Russian Atoll heat-seeking missiles; and selenium, employed in
early television and xerography."
http://en.wikipedia.org/wiki/Photoconductivity
Someone doesn't like povidone-iodine
The mythology of povidone-iodine and the development of self-sterilizing plastics.
http://www.ncbi.nlm.nih.gov/pubmed/8421809
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floggedaway
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I have always considered a kelvin water dropper being a very elementary type of van de graf generator.
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Morgan
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Maybe not earthshaking but interesting ...
New droplet-based electricity generator: A drop of water generates 140V power, lighting up 100 LED bulbs
https://techxplore.com/news/2020-02-droplet-based-electricit...
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![[*]](images/xpblue/default_icon.gif){kind=icon}
