Sciencemadness Discussion Board - Static Electricity

Static Electricity

saps - 17-6-2005 at 10:00

What materials woulkd be best for generating static electricity??

Mr. Wizard - 17-6-2005 at 10:18

That is a little like asking what chemicals would be best for chemistry. A simple quick answer might be a piece of PVC pipe, or rubbing a balloon against a piece of fur. It seems those little styrene plastic packing chips do an amazing job of generating and holding a static charge. What sort of static electricity are you talking about? Are you trying to make a spark or learn about charges? Try using Google and start with static electricity and do sub-searches. If you have some ideas about what you want to do, ask a question here.

What the hell should I do with my old scrached gramaphone records ?

Lambda - 17-6-2005 at 10:59

BUILD A VAN DER GRAAF GENERATOR !

Polish up the fidelity of your old scrached gramaphone records, kick ass in the high voltage zone !, build a Van der Graaf Generator !.

To get a kick-start in the world of static electricity and discharge, here are a few websites with some good links.

http://www.amasci.com/emotor/vdg.html
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/vandeg.h...
http://science.howstuffworks.com/vdg2.htm

Quote:

Did he just stand up, or is it his hair on end ?

saps - 17-6-2005 at 11:49

Mr. Wizard, when you refer to styrene do you meen polystyrene foam

Pyridinium - 17-6-2005 at 13:38

Denim against a PVC / vinyl chair is wicked for making static electricity. Now, how to store this energy... a Leyden jar!!! Somewhere round the lab there is one I made with a nice lacquered wooden cap and a brass knob.

I know, Mr. Wizard, you already mentioned PVC.

Saps, look up Wimshurst Machine on google. LP records, as Lambda mentioned, are best for this kind of setup.

12AX7 - 17-6-2005 at 17:34

Quote:

Originally posted by Mr. Wizard
That is a little like asking what chemicals would be best for chemistry.

Actually it's more like "which metals are better for a battery, iron and copper or zinc and copper, or...?"

There's an electrostatic equivalent of the reduction potential series somewhere out there. A Google should turn something up.

Tim

Mr. Wizard - 18-6-2005 at 08:40

saps,
Yes, I was referring to polystyrene foam chips. Even the blocks of it are very static prone. Static electricity is a general term, usually referring to very high voltages with low currents generated on insulating materials. The fact the materials are usually good insulators, prevents the charge (an excess or deficit of electrons) from moving, thus the term 'static'. Once you start collecting the charge with conductors, you are not technically dealing with static electricity, but high voltage low current. There is a complete spectrum of variations on this .

What is it you are trying to do?

Van De Graaf

MadHatter - 18-6-2005 at 14:09

These generators use a rubber belt, rollers, motor, and pickup combs to charge a sphere.
In the days when I had hair, I could make it stand on end by touching the sphere. Ever considered a
Tesla coil instead ? You didn't state any specifics about voltage, amperage, or even application.

Static electricity, isolators and discharge ?

Lambda - 18-6-2005 at 20:50

I agree with you MadHatter, if you want to get a real show going, then go Tesla. But seeing that Saps is talking about static elictricity, vinyl would be a good and cheap way to go. A rotating record, can be put into a Van der Graaf principle. But as Pyridinium remarked, it can best be used in a Wimshurst configuration. Leather, leather was used in the Van der Graaf, Rubber was rather offlimits in those days. However, it serves no point in going into irrelevant side walks about the subject. It's the principle that counts. I agree with you MadHatter, Saps was not clear about exactly what he intends to do with the principle of static electricity and materials. I tend to then just say: Take the best isolator, go for glass, ceramics, teflon or polystyrene. This would be a dead end for a thread that has such interesting potentials.

I built a Tesla Coil of nearly two meters high, wich gave sparks of about one meter long. The primary coil was triggerd via a "rotating spark gap" and a 15 000 - 20 000 volt capacitor discharge. The primary currents were very high and absolutely deadly. Apart from the fact that people with a pacemaker should avoid such experiments, these sparks were extremely dangerouse. They can easly put your clothes on fire, and give extremely painfull burns, that you find out if/when you wake up again. And then moving becomes a tuff wake up call. Often not mentiond, when talking about high voltages and low currents, is that if it hits you in the eye, vision may go down the drain. There is no need to touch enything solid, for the sparks will find you by themselves. They will come to you and embrass your stupidity with a "warm" welcome.

However, if Saps would be so kind as to be more specific, then maybe we can get something interesting going here.

Quote:

He thought the Faraday cage principle would save him, but as his bodily fluids began to cook, in "shock" he realized that he must have overlooked something !

[Edited on 20-6-2005 by Lambda]

Static electricity

saps - 25-6-2005 at 10:26

I am very confused. I know that objects such as sheets of paper are attracted to staticaly charged objects because both have opposite charges...but why cant batteries make the same affect.

Opposite charges attract each other

Lambda - 25-6-2005 at 12:37

Saps, they do have the same effect, but just not so promenent. The voltages are very low, compared to the several thousand volt static electricity charges you are refering to. If you would put thousands of 1.5 volt batteries head to tail in series, there would be no difference in effect. The only difference would be the high currents involved, and static electricity currents are usually very low. Static electricity charges are collected by isolators, wereby the charge can't flow away. This object then stays charged untill it can relieve itself via a conductor, or a spark jump to an object with an opposite charge (like rain clouds can do). If you would charge a ballon positive, and bring this near the negative pole of the several thousand volt battery, then it would fly towards it. The same would happen if you would bring your baloon near a negatively charged baloon.

Chris The Great - 25-6-2005 at 13:51

Also, keep in mind batteries have no electrical charge relative to other objectives, only the other end of the battery.

So, you'd need to ground the positive end of your several thousand volt battery to get the balloon to fly towards it.

Nerro - 25-6-2005 at 15:25

I I were to separate two metal plates by some (isolating) squishy silicone gel and applied a relative charge of 50 kV to one of the plates (and grounded the other one so that would be 0 V) would the plates move towards eachother like magnets?

Mr. Wizard - 25-6-2005 at 15:34

Quote:

Originally posted by Nerro
I I were to separate two metal plates by some (isolating) squishy silicone gel and applied a relative charge of 50 kV to one of the plates (and grounded the other one so that would be 0 V) would the plates move towards eachother like magnets?

Yes, and the force would be stronger as the plates got bigger or closer together. I don't know if an insulating material separating the plates would have an effect too, but a conductor will change the field.

12AX7 - 25-6-2005 at 17:22

Batteries (DC current) and static electricity are one in the same - look up the Duluc/Zamboni pile (which curiously is also a very close approximation of a perpetual energy source, you'll see why on webpages on the subject).

Tim

Lambda - 25-6-2005 at 17:38

I don't agree about the grounding of the battery. If that were to be so, then bringing the to poles together would never give a spark untill they touch. The spark will jump before they touch, because there is a fieldstrength. A cloud from which lighting hits another cloud is allso not grounded. The fact that this happens is sollumley atributed to a difference in potential, wereby a threshold level is overun. Both sides of the battery will ALLWAYS be charged. If you attach a wire to one end of the battery, then this will allso become charged. How do both of you then think that electricity can sence a potential difference, if there were no fields to determen this by. Dose one baloon have to be grounded to attract another baloon ?. Theoretically, a battery will even try to collaps if there were no way that a spark could jump, and the voltage would go higher and higher. An empty battery would allso be longer than a charged one would be, based on opposite charge attraction and deminishing fieldstrength.

Lambda - 25-6-2005 at 17:41

Sorry Tim, I posted this after you had replied.

Mr. Wizard - 25-6-2005 at 18:10

Quote:

Originally posted by 12AX7
Batteries (DC current) and static electricity are one in the same - look up the Duluc/Zamboni pile (which curiously is also a very close approximation of a perpetual energy source, you'll see why on webpages on the subject).

Tim

Since you brought up these interesting items, the Zamboni or 'dry pile' I'll tell you a very quick and easy way to make one. I've never seen this anywhere else. This won't make sense unless you've read up on their construction; take regular printer paper and spray one side with graphite lubricant. The graphite must be in a non oily base, carried only by a completely volatile solvent. On another sheet of paper spray galvanizing paint, that is a rust preventative paint consisting of powdered zinc in a volatile Toluene solvent. Use a paper cutter or scissors to cut squares (I used 2.5 cm ), and then stack the zinc and graphite sides together, leaving the white paper backs facing each other. Even 4 or 5 of these stacked will register a few volts on a cheap digital volt meter. I never made a big pile, just enough to prove to myself it would work.
You would think the paper would act as an insulator, but it forms a very high resistance battery, which is the whole idea behind a 'dry pile'. Once again the layering is:
-ZPPGZPPGZPPGZP..........PGZPPG+

This is a much cheaper and easier method than using zinc and copper sheets or foil, if you could find them. Breathing a little moisture on the paper will help in very dry climates. You should be able to get 60 to 80 volts with two sheets of paper. More info if requested.

Archimede - 25-6-2005 at 19:50

Quote:

With 50KV I think that before noticing any electromagnetic force you would have an arc blowing thru the insulation.
To create an electromagnetic field you need to have a current flowing thru a conductor. the higher the current the higher the effect. The plate with the 50KV would not have a current flowing.

12AX7 - 25-6-2005 at 19:55

50kV can easily be handled by some 1/16 to 1/8" plate glass, or a much thinner layer of diamond if you can get some wide and flat enough.

Electrostatic force certainly does squash the dielectric, anyone who's worked with pulsing capacitors has seen and heard it.

Tim

Archimede - 25-6-2005 at 20:02

I recall some plastic chair that was biting when I was getting up. You can test different material holding it thru a piece of paper to isolate it from your hand and rubbing it on syntetic fabric. Then just put it in contact to your skin. You will know when you find the right stuff...

Chris The Great - 25-6-2005 at 22:11

Quote:

Originally posted by Lambda
I don't agree about the grounding of the battery. If that were to be so, then bringing the to poles together would never give a spark untill they touch. The spark will jump before they touch, because there is a fieldstrength. A cloud from which lighting hits another cloud is allso not grounded. The fact that this happens is sollumley atributed to a difference in potential, wereby a threshold level is overun. Both sides of the battery will ALLWAYS be charged. If you attach a wire to one end of the battery, then this will allso become charged. How do both of you then think that electricity can sence a potential difference, if there were no fields to determen this by. Dose one baloon have to be grounded to attract another baloon ?. Theoretically, a battery will even try to collaps if there were no way that a spark could jump, and the voltage would go higher and higher. An empty battery would allso be longer than a charged one would be, based on opposite charge attraction and deminishing fieldstrength.

Let me explain. Yes, there is an electrical field between the two poles of the battery. However, that doesn't cause the battery to have a voltage realative to other things. You would need to ground one end to bring the other end to have a high potential towards other things, as the ground has a voltage of 0.

neutrino - 26-6-2005 at 05:28

It would have a potential, just a very weak one. A point charge creates a field, which gives rise to a potential (voltage). The thing is that the charge on a battery terminal is not very big.

Mr.Wizard: That sounds interesting. It sounds like it deserves its own thread.

[Edited on 26-6-2005 by neutrino]

Mr. Wizard - 26-6-2005 at 20:21

I don't know if it deserves a thread, but I'll try to put a demo pile together with some jpegs. I'm not going to make a full sized multi-thousand volt battery, but I'll get enough information together to show how it could be done. I could scan some book pages to attach too.

saps - 27-6-2005 at 10:05

Sry... what i originally meant was: when considering thier useable and positions in the triboelectric series what 2 materials most eficiently produce a negative charge

Triboelectric discharge

Lambda - 27-6-2005 at 11:34

I remember an experiment in which Triboelectric discharge was involved.

When you grind ordinary white crystal sugar in a mortar with a pestill in the dark, then you see light flashes. This phenomenon is due to the breakage of the crystal lactic, thus releasing energy in the form of visible light. Piezo-materials allso behave in a similar manner, but then more focust on lactic-deformation, than rupture.

Saps, are you refering to this phenomenon ?

saps - 27-6-2005 at 15:26

***Sry... what i originally meant was: when considering thier useable surface area and positions in the triboelectric series what 2 materials most eficiently produce a negative charge??

Archimede - 28-6-2005 at 14:18

According to the search done with Yahoo (triboelectric series) the 3 best materials to generate a negative charge are Vinyl(PVC) , Silicon and Teflon.

12AX7 - 28-6-2005 at 18:40

Geez, just Google it.

http://www.rfcafe.com/references/electrical/triboelectric_se...

Farther away they are, the more potential made. K?

Tim

Marvin - 29-6-2005 at 13:49

Does it bother anyone else that sulphur and polyethylene are on the list twice each in different positions?

Simon - 29-6-2005 at 17:08

Quote:

Originally posted by Chris The Great
[Let me explain. Yes, there is an electrical field between the two poles of the battery. However, that doesn't cause the battery to have a voltage realative to other things. You would need to ground one end to bring the other end to have a high potential towards other things, as the ground has a voltage of 0.

The poles of a battery do have a voltage relative to "other things".

If you touch a charged sphere hanging in the air, you get a shock because it has a voltage relative to the ground, even though it is just a sphere hanging in the air.

It has a voltage relative to the ground thanks to its capacitance to ground (in other words, the way its electric field interacts with the ground). In the same way the poles of a battery have a capacitance to ground and its electric field interacts with the ground. Since the voltage and capacitance involved are small the affect is hard to notice.

If a battery had poles of the same sort of area and voltage as the original charged sphere, you could experience a shock from at least one of the poles.

Oxydro - 29-6-2005 at 17:30

Sure, the poles of a battery can have a voltage relative to "other things". But, there is no reason for them to have such a voltage unless they are somehow linked to said other things. A battery is a closed system, untill you attach it to something else. A sphere can have a charge, but it needs to interact with its surroundings to get that charge. Same with a battery.

If you suspend either a sphere or a battery, without charging it *relative to ground* it will have no charge, to you, untill you are connected with one of the battery's poles.

To have fieldstrength mean anything, it has to be relative to something, eh? A cloud doesn't need to be grounded to make lightning -- a charge has built up and then is released.

neutrino - 29-6-2005 at 18:38

The standard reference point in these cases is zero, the potential/field strength at infinity.

Think about it this way: both poles can’t be neutral.

Marvin - 29-6-2005 at 19:32

This is both more difficult and easier than it looks. In the first part field strength does not have to be relative to anything, its change in potential over distance, ie a derivitive.

There is nothing to stop a field/potential existing between a battery terminal and ground but its not possible to say what this is, it depends on everything else. Batteries arn't electrostatic, they are electrodynamic.

In electrostatics its easy to define what ground is, as matter starts off neutral.

Oxydro - 30-6-2005 at 05:20

Ok, Marvin, I guess I misspoke (mistyped?) myself slightly. When I said it has to be relative to something, I meant more that it need to differ in potential from something, else there is no change in potential so no field.

Neutrino, I take it you are saying something like, since there is a potential difference between the two poles, then only one can be the ground reference if indeed either is. So the minimum possible potential at one pole, is if the battery is exactly net neutral, therefore a pole is +or- E/2 with respect to ground.

I see what you are saying, and I have to admit it seems to be right...

neutrino - 30-6-2005 at 07:45

Couldn't batteries be considered electrostatic also? The battery is going to pump some electrons from the positive terminal to the negative, creating a pair of point charges. There wouldn’t be much charge, as I said earlier, but it would be there.

12AX7 - 30-6-2005 at 13:39

Exactly. The ONLY difference between common direct current and static electricity is the scales of voltage and current. A Zamboni pile stacked to say 20,000 will easily blur that difference.

Tim

Simon - 30-6-2005 at 15:24

Quote:

Batteries arn't electrostatic, they are electrodynamic.

Electrodynamics is electricity that's moving, electrostatics is electricity that isn't. It's the same electricity and the same voltage, charge, capacitance and resistance.

Neutrino is quite correct in saying that if there is a pd between the terminals of the battery (which you'd hope so), then they can't both be neutral. That is what I was referring to in my post when I said you would have to experience a shock from at least one of the terminals if the voltage were high enough.

To avoid confusion, I'll clarify that I'm not saying the voltage to ground has anything to do with the emf of the battery beyond this fact.

[Edited on 30-6-2005 by Simon]

Marvin - 30-6-2005 at 15:29

A battery isnt a source of potential, its a source of relative potential between two conductors. Whats more essentially unlimited charge is allowed to flow between them in order to maintain it. This doesnt square very easily with classical electrostatics where voltages are assumed to result from charge, rather than the other way around.

Simon,

"Electrodynamics is electricity that's moving, electrostatics is electricity that isn't."

A battery is an electrodynamic element, its only meaningful when current is flowing. While its true to say there is a charge difference between the terminals in the static state, it isnt possible to say what those charges actually are. If you replace those elements by charged terminals you can have the same EMF between them, but the problem now always has a solution. The item is nolonger a battery, but the only difference occurs when things actually change.

"It's the same electricity and the same voltage, charge, capacitance and resistance. "

Resistance is not meaningful unless current is flowing so its not right to argue that an electrostatic picture contains the same basic elements.

"Neutrino is quite correct in saying that if there is a pd between the terminals of the battery (which you'd hope so), then they can't both be neutral. "

Of course they can both be neutral, just not at the same time.

"That is what I was referring to in my post when I said you would have to experience a shock from at least one of the terminals if the voltage were high enough. "

The voltage does not come into it, assume you are neutral, charge will flow but the amount also depends on the capacitance of the electrodes. This could be anything and the shock itself is of course dynamic flow that has nothing to do with the actual battery.

[Edited on 30-6-2005 by Marvin]

12AX7 - 30-6-2005 at 16:15

Ideally yes, but when you observe a battery for a long period of time, the zinc is eventually consumed and it runs out of <I>charge</I>.

Neat thing about electrochemistry and electrostatics...both work on individual electrons like that.

Tim

Simon - 30-6-2005 at 16:24

Quote:

Originally posted by Marvin
The voltage does not come into it, assume you are neutral, charge will flow but the amount also depends on the capacitance of the electrodes. This could be anything and the shock itself is of course dynamic flow that has nothing to do with the actual battery.

The voltage of the battery does come into it in a sense, while it is still not the same voltage as the voltage to ground. Otherwise this quote doesn't contradict anything I've written, so we seem to be mostly in agreement. Same goes for most of the rest of what you wrote.

The difference seems to be in the idea that there is something specially different about static electricity and dynamic.

Marvin - 30-6-2005 at 18:20

The battery example came up because the concept of isolated circuits was being applied in electrostatic terms. In electrostatics isolated circuits (in which a voltage needs a point in the same circuit to be relative too in order to have any meaning), capacitors, batteries, inductors and resistors do not exist.

The idea that theoretically a battery must give a shock from one or the other terminal is false. If you take an ideal battery you can assume the capacitance of the terminals is zero. We can touch one terminal assuming we are ground and regardless of battery voltage no current needs to flow - we do not get a shock. If we then let go and touch the other terminal even though the official polarity is now switched still no current needs to flow. In the real world capacitance is unavoidable and with an EHT battery a shock could be felt but this effect is almost solely caused by other factors.

While a battery can be a source of static electricity, from a purely electrostatic viewpoint it does not exist.

neutrino - 30-6-2005 at 18:38

Yes, my point was that we don’t exactly live in an ideal world and a few extra electrons are going to lie at the negative terminal and a few will be missing from the positive. I guess I really should start explaining my ideas a little better.

Simon - 1-7-2005 at 17:38

This is getting idiotic.

The original statement was that the terminals of the battery have no voltage "relative to other things", unlike a charged sphere.

I pointed out that there is nothing special about the battery and that all things have a relative potential, even if that is 0.00V, thanks to capacitance.

In other words the interaction from electric fields.

In yet other words, the integral of the electric field intensity across distance.

Accepting this leaves everything unified and integration a safe pastime. You can call a particular capacitance negligable, but saying it doesn't exist is theoretically unsound and leads to problems which are unneccessary, since there is always capacitance.