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An electrostatic mystery ...

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Michael Gilligan01/03/2015 09:33:41
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14244 forum posts
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In 1759, the Royal Society published papers by Robert Symmer; documenting in detail some experiments with static electricity.

The papers are available here, and make fascinating reading.

**LINK**

So far as I am aware, no one has explained his curious finding; that Black and White Silk became oppositely charged !!

I should warn you that the papers run to 55 pages. [But they are probably more interesting than the News.]

MichaelG.

Brian Wood01/03/2015 13:18:38
2008 forum posts
37 photos

Thank you Michael, you can be relied upon to bring interested and sometimes obscure material out for the rest of us to enjoy.

Brian

Gordon W01/03/2015 13:51:50
2011 forum posts

Michael- where do you find this stuff? I n my very limited experience nobody has given a convincing explanation of static electricity anyway. Tried to understand how Wimshurst ,and the like, machines work, every body has a different idea, even up to modern times.

John McNamara01/03/2015 14:10:46
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Hi Michael

I suspect the charge polarity (Or maybe just the lack of a charge because the black dyed silk conducted the charge away) may have been the cause.

Before aniline dyes were discovered in the early 1800's many naturally occurring minerals and substances were used including Iron, many other materials are also conductive. If you Google "medieval black silk dye" you will find some useful links.

Regards
John

Michael Gilligan01/03/2015 14:57:14
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Thanks for the replies,

I found the papers because they are properly referenced in this wonderful book by Joseph Priestley.

... My favourite Reference Library [John Rylands, on Deansgate, Manchester] has it.

.

John: You are probably right about the dye. ... What I find particularly interesting is that, in those early days of discovery; he presents a detailed experimental narrative, but doesn't quite reach that conclusion.

MichaelG.

Edited By Michael Gilligan on 01/03/2015 14:58:48

Ian S C02/03/2015 05:51:51
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Sound similar to those little rotating crosses in the glass envelope that looks like a light bulb, on the end of the arms of the cross is a small square, black on one side, and white on the other. Sit it in sun light, and it spins. it's got a name, can't remember it just now.

Ian S C

Michael Gilligan02/03/2015 07:50:30
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14244 forum posts
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< UPDATE >

I just found this page, which may be of interest.

MichaelG.

modeng200002/03/2015 07:50:40
214 forum posts
1 photos

I know them as solar windmills. Can't find the proper name for them though.

John

Michael Gilligan02/03/2015 08:13:56
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14244 forum posts
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Posted by modeng2000 on 02/03/2015 07:50:40:

I know them as solar windmills. Can't find the proper name for them though.

.

Crooke's Radiometer

MichaelG.

Johan van Zanten02/03/2015 08:13:59
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52 forum posts
98 photos

Hi Ian and John,

Do you mean the radiometer from Crookes?


**LINK**

Regards, Johan.

Ian S C02/03/2015 09:27:47
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Johan/Michael, thanks for that. I,v got another machine I made a good many years back, it has a steel centre column, on top of which a bit of wire about 4" long balances on a very free bearing, the ends of this wire are bent horizontally 1/2", if the static electricity is applied to the centre column the wire on top revolves on it's pivot. The bloke who invented that had a name starting with H (I think).

Ian S C

jason udall02/03/2015 09:54:45
2012 forum posts
41 photos
With apologies for not having read the referred document.. ( saving it for later)...

I guess the intrest is in the different ( polarity?)
Of charge induced when rubbing two dissimilar materials ( black and white silk?) Over say a glass rod.. why would one produce a different polarity? ..
Well if the two were rubbed close to each other then one would ( even if oh so slightly) be more positive. .this would enduce a more negative on - in the other which in turn enduces more + in the other..etc.
Have a look at kelvins cans or similar search...this uses water for both moving parts and obviously these are identical but still charge seperation happens and is amplified
Michael Gilligan02/03/2015 10:25:38
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14244 forum posts
627 photos

Jason,

Glad to have you on-board, pondering this one!

I think important that you do read his papers when you have time ... He seems to have tried all the permutations before concluding that the colour was the important factor.

As John suggests; I think the dye will prove to be significant.

Interestingly; I have searched on the Royal Society page, and can find no follow-up mentioning Symmer by name.

MichaelG.

Edited By Michael Gilligan on 02/03/2015 10:27:44

John McNamara02/03/2015 12:36:04
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1309 forum posts
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Other devices that comes to mind are the electroscope....
**LINK** used by the early experimenters to measure charge..

The Leyden Jar a kind of capacitor was the main source of energy **LINK**

The battery had to wait until later **LINK**

Fascinating times

Regards
John

Michael Gilligan02/03/2015 12:53:44
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14244 forum posts
627 photos
Posted by John McNamara on 02/03/2015 12:36:04:

Fascinating times

.

Indeed they were, John

The state of understanding of electricity was about where we are now with 'Dark Energy', and some of the experiments that they did are astonishing! ... I feel sure you will appreciate this book by Joseph Priestley, that I linked earlier.

MichaelG.

.

P.S. ... YouTube video from M.I.T.  about the Wimshurst Generator, here ... might be useful if you want to experiment on small children and innocent animals. devil

Edited By Michael Gilligan on 02/03/2015 13:01:31

Gordon W02/03/2015 14:10:22
2011 forum posts

Thanks for the Wimshurst video link, thats the usual sort of explanation, but I still don't believe it. I've already done the tests on small children.

Ian S C03/03/2015 09:54:04
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7447 forum posts
230 photos

There is some interesting model engineering projects in the way of electrostatic machines, many and varied, a lot of brass, glass, and wood/ebony. don't worry, gold leaf is not too expensive.

Ian S C

modeng200003/03/2015 11:17:16
214 forum posts
1 photos

This link takes you to lots of electrostatic machine information.

Enjoy

http://www.coe.ufrj.br/~acmq/links.html

John

Edited By modeng2000 on 03/03/2015 11:18:58

Edited By modeng2000 on 03/03/2015 11:20:15

Russell Eberhardt03/03/2015 11:31:49
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2496 forum posts
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All this talk of electrostatics reminds me of school physics lessons. We had Leyden Jars, a Wimshurst machine, gold leaf electroscope, sticks of ebonite for rubbing with silk, and even a Van der Graff generator. Do school labs still have all those I wonder?

Russell

Ian S C04/03/2015 08:03:34
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7447 forum posts
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I think the local high school does have some gear, they also have an HT Neon sign transformer of mine, must see how they got on with that.

I seem to remember using a couple of strips of aluminium foil in place of gold leaf for an electroscope.

Ian S C

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