An electrostatic mystery …

[Michael GilliganParticipant @michaelgilligan61133]

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.

[Michael GilliganParticipant @michaelgilligan61133]

[Brian WoodParticipant @brianwood45127]

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 WParticipant @gordonw]

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 McNamaraParticipant @johnmcnamara74883]

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 GilliganParticipant @michaelgilligan61133]

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 CParticipant @iansc]

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 GilliganParticipant @michaelgilligan61133]

< UPDATE >

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

MichaelG.

[modeng2000Participant @modeng2000]

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

John

[Michael GilliganParticipant @michaelgilligan61133]

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 ZantenParticipant @johanvanzanten]

Hi Ian and John,

Do you mean the radiometer from Crookes?

**LINK**

Regards, Johan.

[Ian S CParticipant @iansc]

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 udallParticipant @jasonudall57142]

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 GilliganParticipant @michaelgilligan61133]

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 McNamaraParticipant @johnmcnamara74883]

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 GilliganParticipant @michaelgilligan61133]

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. 

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

[Gordon WParticipant @gordonw]

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 CParticipant @iansc]

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

[modeng2000Participant @modeng2000]

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 EberhardtParticipant @russelleberhardt48058]

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 CParticipant @iansc]

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

[John OlsenParticipant @johnolsen79199]

I have a Wimshurst machine. It was originally built by my father, and restored by both of us during the 60's. It is now in need of a bit more restoration, which I hope to find time for soon. As to the principal that it works on… The main thing is charge separation, eg if you have a charged capacitor and you pull the plates apart, the Voltage will increase. This is reasonable enough, since you have reduced the capacitance so for the stored energy to remain the same the Voltage must go up. All very well, but where does the initial charge come from? Anyway, they work fine and are fun to play with, especially in a darkened room. They tend not to work so well in damp conditions. I think this one was originally described in ME, although it would be before the forties, which is where my own collection starts. When you start turning the handle, you can feel the load come on when the machine begins to charge.

Different materials tend to give different polarities when rubbed, and I would agree that probably the dye is making the difference.

Did you know that pulling sellotape off the roll generates low energy X-rays? If you do that in the dark you can see sparks too.

The Faraday Centre in Napier (a technology museum) has a Tesla coil…now that makes some serious sparks.

John

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by John Olsen on 05/03/2015 00:34:01:making the difference.

Did you know that pulling sellotape off the roll generates low energy X-rays?

Err . . . . Aren't all X-rays high energy by virtue of their short wavelength?

Russell

[Ian S CParticipant @iansc]

During most of my working life I was a nurse, and a good place to find (and have fun with) is when making the beds in the morning, whip a sheet off the bed, the hold your finger 1/2" away from a radiator, or other earth point, and BANG, a good fat spark.

Ian S C

[Danny M2ZParticipant @dannym2z]

The school that I went to in London as a kid was Parmiter's Grammar School in Bethnal Green (London).

The school had fantastic science labs with Wimshurst machines, Kundts tubes, Roentgen tubes, precision chemical balances in glass cases, a planetarium, and an art teacher (G.R.Williams) who was in 'Who's Who'. The school even had a photography club with a well equipped darkroom for after hours use.

After 4th form one was allowed access for practical studies (not the chem lab, unfortunately) so many fascinating experiments were devised. I wound a Tesla coil one day and used it to demonstrate to parents on an open night how to make lightning come from my fingers – exciting stuff at 15, but more fun was running a battery through soapy water and lighting the bubbles with a wax-taper. One day my home-made radio picked up the BBC broadcasting a computer playing music "Daisy" – thus I was hooked.

Nowaday's elfin safety would crack down on such adventures, but I have kept an eye on the old school, they have re-located. I hope that they kept the old tools that made a kid so inquisitive.

* Danny M *

[Author]

Posts