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Where can I find an electrostatic series,
that is, how easily a substance is charged by
friction and how positive or negative it becomes?
Prof. Eric T. Lane 318 Grote Hall 423-755-4523 eric-lane@utc.edu
Physics Dept.2352, University of Tennessee at Chattanooga, TN 37403
From: Leigh Palmer <palmer@sfu.ca>//
The Wimshurst machine is a self-excited electrostatic generator
in the operation of which friction (triboelectricity) plays no
fundamental role.
// The
electrophorus (and some Van de Graaffs) is an induction machine
in which the polarity may be determined by triboelectricity, but
the sustained operation of which depends solely on induction.
For triboelectricity to be an important ongoing mechanism in the
operation of an electrostatic generator there must be some
intrinsic asymmetry present.
Leigh
From: William Beaty <billb@eskimo.com>//
/// several were mentioned in "Flying Circus of Physics with
answers." Several in Am. J. of Physics were mentioned there
The upshot: the triboelectric series is valid for contact, but not for
friction. When flat samples were passed between rollers, the polarity was
replicable, but when they were rubbed, results varied, and surface finish
then became important. There was evidence that thermal effects were
important, and when a long object was stroked across a tiny spot on
another object, polarity was different than when it was stroked along a
wide area of the second object. And in violation of conventional wisdom,
when *identical* materials but with differing roughness were rubbed
together, charge separation was significant!
From: Martha Takats <mtakats@acad.ursinus.edu>
For a table of the "triboelectric sequence", see Hecht's Physics
(Brooks-Cole 1996), p. 174.
From: kfox@shhs1.smoky.org (Ken Fox)
Triboelectric Series
(...a series of relative affinities ~
positive and negative charges)
MORE POSITIVE
rabbit's fur
glass
mica
nyIon
wool
cat's fur
silk
paper
cotton
wood
acrylic
cellophane tape
polystyrene
polyethylene
rubber balloon
saran wrap
MORE NEGATIVE
Ken Fox
From: William Beaty <billb@eskimo.com>
Here's another, http://www.eskimo.com/~billb/emotor/statelec.html
When various materials are rubbed together, which becomes positive
and which negative? Ah, you want the...
TRIBOELECTRIC SERIES
Air *
Human Hands <---- Most Positive
Asbestos
Rabbit Fur
Glass
Mica
Human Hair
Nylon
Wool
Fur
Lead
Silk
Aluminum
Paper
Cotton ZERO
Steel
Wood
Amber
Sealing Wax
Hard Rubber
Nickel, Copper
Brass, Silver
Gold, Platinum
Sulfur
Acetate, Rayon
Polyester
Styrene (Styrofoam)
Orlon
Saran
Polyurethane
Polyethylene
Polypropylene
Vinyl (PVC)
Silicon
Teflon <----- Most Negative
The above list is from NATURE'S ELECTRICITY, p63
by Charles K Adams (c)1987 Tab Books, #2769
From: msantos@etse.urv.es
How [does] symmetry make friction irrelevant?
From: Leigh Palmer <palmer@sfu.ca>//
Asymmetric electrostatic generation by friction: rub A on B and A//
always becomes positively charged while B becomes negatively charged.
Symmetric electrostatic generation by friction: rub A on A and A
sometimes becomes slightly positively charged and sometimes
negatively charged.
The generator may be biased initially by charging one terminal
with a cat fur rubbed hard rubber rod. That terminal will become
the negative terminal when a symmetric machine is started up.
Otherwise some small asymmetry will determine the polarity.
You should cosult a source for an explanation. "Traite' E'lementaire///
d'Electricite'" by Joubert, or its translation, "Elementary Treatise
on Electricity and Magnetism" by G.C. Foster and A.W. Porter, 2ed,
Longmans, Green & Co. (1903), section 78, p 110, or "The Elements of
Electricity and Magnetism" by Franklin and MacNutt, Macmillan (1908)
are the books that come readily to hand in my office. Descriptions
of Wimshurst's machine seem to be missing from most modern texts
Leigh---------------------
From: Joseph Bellina <jbellina@saintmarys.edu>//
There are/were a variety of induction machines.
One that was very common in Europe in the last century was a Holtz
machine. It differs in appearance from the Wimshurst since it has only
one rotating plate.
From: "GARY HEMMINGER" <Hemmig@d-e.pvt.k12.nj.us>
Can anyone give a description of the exact mechanism for one of the
common effects that we see in the lab: e.g. rubber rods become
negative when rubbed with fur. My students are always curious
about this, and I while I want them to understand that there are a
few possibilities; transfer of electrons, transfer of negative ions,
transfer of positive ions, or combinations of these, I'm interested to
know exactly what is known about this.
From: Joseph Bellina <jbellina@saintmarys.edu>
/// there is no good working theory which
explains the transfer of charge due to rubbing...
From: LUDWIK KOWALSKI <KOWALSKIL@alpha.montclair.edu>
34) Triboelectricity is not caused by friction. It is caused by
intimate contact between dissimilar insulating surfaces.
From: Joseph Bellina <jbellina@SAINTMARYS.EDU>//
I think the presentation in Sherwood and Chabay which suggests that the
tranferred materials are ion fragments rather than electrons is probably
a more correct model. The point they make (and I really shouldn't speak
for them...look on or about page 16 of their text) is that these
materials are mostly polymers so it is easy to imagine ion fragments
being transferred.
Recent work modelling what happens when metals touch indicates that
there is material exchange
/// I see vague model statements in Hecht...// Hecht speaks in
terms of electron transfer, Chabay and Sherwood in terms of ion
transfer...neither is very quantitative.
wrote:///this is a lab exercise we have our students (11th and
Joe, your reply sent me off to my collection of introductory physics
texts. // I did find a reference to it in Hecht's calculus-based text (p.
647, in the 1996 edition)
12th graders) do every year, with a few objects (Saran wrap, rabbit
fur, plastic, Scotch tape, Styrofoam, wool, and a few others). Their
task is to arrange the objects they are given in an order such that
the object at the top of the list will transfer electrons to any
object below it on the list, the one on the bottom will pick up
electrons from any one on the list above it, and those in between
will give up electrons to those below and accept electrons from those
above (I think that's the normal order). According to Hecht, this is
called a triboelectric series
From: "John S. Denker" <jsd@MONMOUTH.COM>
1) "Triboelectric" is a perfectly good word that refers to electrification
by rubbing. Since rubbing is now seen to be a somewhat peripheral issue,
the more "in" term (and the more physical term) is "contact electrification".
2) It has been known for about 200 years that, strictly speaking, there is
no such thing as a triboelectric series. Depending on the chemical and
physical state of the surfaces, I can create objects A, B, and C that obey
the nontransitive relationships
x(A,B) > 0
x(B,C) > 0
x(C,A) > 0
where x(,) designates the charge of the first object when
contact-electrified against the second. It is even possible to have two
objects D and E such that
x(D,E) > 0 if you rub gently, while
x(D,E) < 0 if you rub harder.
A related but easier-to-visualize piece of physics is this: given fixed
terminals (A1 and A2) made of absolutely identical material (A) plus a
moving part of type B, I can create a generator which uses contact
electrification to move charge from A1 to A2 at a steady rate. Does that
imply A > B > A????
3) There _is_ such a thing as a work function, which is one of several
physical properties that contribute to contact electrification. The work
function itself is hard to pin down, since it depends on the chemical and
physical history of the surface. But it can be measured, e.g. by a Kelvin
bridge (which I am told was not invented by Kelvin).
4) I don't know of an accessible pedagogical discussion of contact
electrification. It's a complicated phenomenon, but reasonably well
understood. Back when I was a grad student the kind folks at Xerox let me
pick their brains (and their library) on the subject. Mostly it's just a
combination of everyday things:
-- work function
-- capacitance
-- tunneling and/or corona
-- simple fluid flow
-- etc.
On Tue, 18 Apr 2000, Hugh Haskell wrote:
the student asked the question "What
is the theoretically accepted model that explains the triboelectric
series?"
but later; maybe not this topic, but some other that may interest him
more), then I would mark him as a serious student of science, worthy
of support, but support by not giving easy answers to all his
questions. If not, then he is not a serious student and we lose
nothing by not providing the easy answer he seeks.
I would not take this tack on every question asked, but this one is
particularly suited to direct investigation, and seems a good one to
try out Donald's suggestion on.
Hugh
recently weChavezCL@aol.com writes:
Mr. Ken Fox,
My name is Christopher Chavez and I am a senior at Central High
School in
Phoenix, Arizona. I am enrolled in an AP Physics class and
organization, mycame
across the triboelectric series. Unable to explain its
that youteacher has asked me to research this topic. I found your chart
question is:have on the web and later discovered your email address. My
> What is the theoretically accepted model that explains the
triboelectric>series?
From: Hugh Haskell <hhaskell@MINDSPRING.COM>
/// if
there is no reliable model to explain triboelectricity, and if there
is no reliable way to create a repeatable series, then it might have
even more value as a student exercise. Just about everything we do in
an introductory class "has an answer." But in real science, there is
no guaranteed answer
Eddington is reputed to have said, "When an investigator has
developed a formula which gives a complete representation of the
phenomena within a certain range, he may be prone to satisfaction.
Would it not be wiser if he would say, 'Foiled again! I can find out
no more about nature along this line.'"
Hugh
From: David Bowman <David_Bowman@GEORGETOWNCOLLEGE.EDU>// given fixed
terminals (A1 and A2) made of absolutely identical material (A) plus a
moving part of type B, I can create a generator which uses contact
electrification to move charge from A1 to A2 at a steady rate. Does that
imply A > B > A????
Along these lines it is even possible to have x(A,A) > 0 where the
substance A of the first argument is chemically the same with the same
crystal structure as the A of the second one with the only difference
between them being their temperature. Not only this, but which direction
the charge is transferred relative to which way the temperature imbalance
goes *itself* can be temperature dependent.
A nearly ubiquitous example (and maybe "dramatic" enough to suit Leigh,
but going strictly by memory/memorism) is that of the electrification
that takes place in thunderstorm cells. Ice contacting ice at a
different temperature will transfer charge. Which way the charge is
transferred relative to the temperature difference is itself (as I think
I recall) a temperature dependent property.
David Bowman
From: "Glenn A. Carlson" <gcarlson@MAIL.WIN.ORG>//
If there is no such triboelectric series, perhaps, there could be one
based on the combination of pairs of materials. The entries in the
series would be arranged according to a single numerical value
analogous to friction coefficients which also depend on the
combination of materials in contact.
Webster's //
Regards,
Jack
But it does appear in Physics textbooks, see e.g.
Intermediate level
Harnwell, Principles of Electricity and Magnetism
Introductory Level
Lea & Burke, Physics: The Nature of Things
and others (but it isn't ubiquitous in US Physics texts)
From: Rick Strickert <rick_strickert@URSCORP.COM>
There're over 90 URL sites I found in less than a minute with a search
engine using the phrase "triboelectric series". One site includes a 1998
paper, "ESD and the Electronics Industry" with a Triboelectric Series table
of materials at
http://www.engr.uvic.ca/~gatoews/ESD/Materials/body_materials.html#table3.
From: William Beaty <billb@ESKIMO.COM>///
The bulk resistivity of the ferrite specimen was very high,
but the measured voltage was not entirely consistent with a motional EMF.
There appeared to be a considerable triboelectric component - and the
abrasive quality of the surface at the considerable peripheral speed
involved was hard on the probes. I saw values hovering around
30 millivolts in one run.
But I took no care to neutralize the geomagnetic field, which itself
provides the basis for a conventional style Faraday generator.
Idea: if you run the magnet CW and then CCW, the difference in absolute
P.D. would indicate a homopolar-generator effect, while the average of the
readings would indicate some other phenomenon such as the Tolman effect
(free electrons pushed to the rim by centrifugal action.) If you flip the
entire experiment around by 180 degrees while running the magnet in the
same direction, any changes in P.D. would probably be due to the earth's
field.
From: Joseph Bellina <jbellina@SAINTMARYS.EDU>
Triboelectric means charging by rubbing...there is no good model to
explain it.
From: John Denker <jsd@MONMOUTH.COM>
At 05:00 PM 4/19/00 -0500, Rick Strickert wrote:///
There're over 90 URL sites I found in less than a minute with a searchhttp://www.engr.uvic.ca/~gatoews/ESD/Materials/body_materials.html#table3
engine using the phrase "triboelectric series".
On the page Rick cited I was amused by the confident ordering of paper >
cotton > wood. I also snickered at the listing of highly reactive
substances with no mention of surface state or history. Are they really
talking about aluminum, or some oxide on the aluminum surface? And was the
glass recently washed in acid, or alkali, or what? If you know anything
about contact electrification, you know such things make a huge difference.
From: "John S. Denker" <jsd@MONMOUTH.COM>//
This thread started out with the question of how to understand the
"triboelectric series".
Philosophical point: It is good to train students to answer the question
that _should_ have been asked, not just the question that was actually
asked. This is a crucial skill in the real world, all-too-often
undervalued in the classroom.
In this case, a good move might be to morph the topic toward "work
function." Note that that altavista reports 5165 references to that,
versus 93 references to "triboelectric series".
From: Joseph Bellina <jbellina@SAINTMARYS.EDU>// moving to a discussion of work-function might be a useful
educational activity since there is more data, and the topic appears to
be simpler.
in terms of ionic transfer by polymer fragmentation may be a more
fruitful model for explaining the series.
///A van de Graaff Generator is self-excited. If it is symmetrical
(top and bottom takeoff brushes identical) it should be possible to
produce either polarity of charge on the dome. I've tried initially
biasing our vdG with a battery, but I always get the same final
polarization direction. Should I try a Wimshurst to bias it?
Leigh
From: "Bernard G. Cleyet & Nancy Ann Seese" <georgeann@REDSHIFT.COM>
I forgot to mention the vacuum cleaner VdG I saw built bydid work "well."
a "gentleman scientist" in Sta. Barb. back in the 50's.
the "belt" was mica chips recirculated by the wind created by the
vacuum cleaner. Since that was ~45 years ago, I remember no details. It
paint will better
bc
P.s. You all know about painting systems where a charge is applied so the
cover uneven surfaces, etc.? In the research dept. of the Fredrich Listzschool (National
Railway School) in Dresden (DDR regime), one of the engineers showed methe system he was
developing using triboelectricity so an HV P/S was unnecessary.
William Beaty wrote:assuming that the
On Wed, 17 May 2000, Bernard G. Cleyet & Nancy Ann Seese wrote:
Here's a question many of you (I presume) know. If I'm correct in
bottom pulley, whatcharge ferried up is generated by the separation of the belt from the
is the purpose of the bottom set of needles?
In the tabletop VDG machines I've seen, the rollers act as the "cake" of
an electrophorus, while the comb acts as the grounded finger. The moving
belt acts both as the metal electrophorus plate, and as the wool which
charges the cake. Once charged, the roller can function continuously
without needing any further charging. The charged roller induces the
combs to spray charge upon the belt. Or from another perspective, the
grounded comb is trying to discharge the plastic roller, but the
insulating belt keeps intercepting the flowing charges.
Here's a diagram:
http://www.eskimo.com/~billb/emotor/belt.html
Also VDG machine page:
http://www.amasci.com/emotor/vdg.html
From: William Beaty <billb@ESKIMO.COM>
On Fri, 27 Oct 2000, Frank Gross wrote:
--- comments ---
Bill,
I am a university professor now delving into electrostatics and
triboelectric charging. I recently completed a NASA project on testing
the charging of Martian sand. I have the opportunity to teach an
advanced fields class this spring and want to teach on the general
subject of electrostatics, tribocharging, adhesion, precipitation,
discharge, etc... I am having a real hard time finding a textbook that
really deals with all of these subjects. H have harpers book but it is
principly empirical with few equations. I have Niels Jonassen's book
which is similar. Can you recommend a text that really gets into all
aspects but from a physics perspective? (contact charging, adhesion,
dissipation and discharge?)
Thanks,
Frank
From: "Daniel L. MacIsaac" <Dan.MacIsaac@NAU.EDU>//
a partial list from an earlier PHYS-L post is at
<http://purcell.phy.nau.edu/new_seatexp/resource/tribelec.htm>
from activities at
<http://purcell.phy.nau.edu/new_seatexp/index/index.htm>
The archives have quite a lot to say about (particular caveats) these
triboelectric series
From: William Beaty <billb@eskimo.com>
Ya gotta admit that the "Static Electricity Is Caused By Friction"
misconception has extreme difficulty finding a mental niche in a person
who has been innoculated by the "sticky electrostatics" demo.
From: Leigh Palmer <palmer@sfu.ca>/// what was perhaps the prototype of all electric
-----------------------------------------------------------generators - a ball of sulphur turned with a handle was charged by
stroking the rotating surface with the hands.
This was undoubtedly described as frictional charging.
Leigh