Date: Fri, 18 Feb 2011 08:38:40

Author: Dan Bernoulli

Subject: Re: Tin Foil Capacitor

Post:

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Yes=2C wire leakage may be a significant problem. Get teflon insulated wire=
s or other "low leakage" insulated wires. Keep them well away from other su=
rfaces. Make sure the connections on your electometer are squeeky clean by =
washing with alcohol. Any surface that the apparatus touches should be an i=
nsulator and squeeky clean as well.

Dan Beeker

> From: keith.warren@ncsu.edu
> To: tap-l@lists.ncsu.edu
> Subject: Re: [tap-l] Tin Foil Capacitor
> Date: Thu=2C 17 Feb 2011 16:59:50 -0500
>=20
> You are keeping your wires off of the table right? I have not tried this
> demo yet but I know from recent trouble shooting that normal lab wires wi=
ll
> discharge an electroscope pretty quick if they are lying on the lecture
> table. The coating is not rated for such high voltages.
>=20
> -Keith
> ncsu
>=20
> -----Original Message-----
> From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
> Behalf Of Paul Nord
> Sent: Thursday=2C February 17=2C 2011 4:41 PM
> To: tap-l@lists.ncsu.edu
> Cc: Paul Nord
> Subject: Re: [tap-l] Tin Foil Capacitor
>=20
> Dale=2C
>=20
> You should have tried it last week. Much too warm today. You probably n=
eed
> to be quick or do this with very low humidity.
>=20
> There were a couple of things said in that article that confused me.
> Perhaps the experts can shed some light on this. In the last paragraph t=
he
> author mentioned that this effect wouldn't work if you had insulating lay=
ers
> between the rolls of foil. Though he seems to imply that he has not trie=
d
> this. Would a coil of a single foil with a insulating layer have a highe=
r
> capacitance than a conducting tube? Wouldn't the charge simply move to t=
he
> outside surface?
>=20
> Second point of confusion. The entire demonstration is intended to infer
> that a charged rod has a lower capacitance than a flat sheet. Yet the
> author suggests that this would not work if the foil were wrapped on a
> conducting rod. Or was he only intending to say that this wouldn't work =
if
> the rod were grounded?
>=20
> Paul
>=20
> On Feb 17=2C 2011=2C at 3:24 PM=2C Dale E. Stille wrote:
>=20
> > Tappers=2C
> >=20
> > Anybody do the "Tin Foil Capacitor" demo by Frank Noschese that was
> mentioned on page 621 of the Dec. 2010 TPT. Basically you have a roll of
> tin foil connected to a electroscope. When you charge the electroscope a=
nd
> then unroll the tin foil the voltage goes down=2C and when you roll it ba=
ck up
> the voltage returns to the original value.
> > My problem when I try to set this up is the voltage leaks off this at
> about 1000 V. per minute which make it unusable for me. I have narrowed =
it
> down to the fact that the voltage is leaking directly off the tin foil. =
I
> imagine there is some trick to making this work like the video that went
> along with the article but I ain't catching it.
> > Can somebody clue me in??
> >=20
> > Thanks=2C
> > Dale
> >=20
>=20
>=20
>=20
=

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Yes=2C wire leakage may be a significant problem. Get teflon insulated wire=
s or other "low leakage" insulated wires. Keep them well away from other su=
rfaces. Make sure the connections on your electometer are squeeky clean by =
washing with alcohol. Any surface that the apparatus touches should be an i=
nsulator and squeeky clean as well.Dan Beeker>=3B From: k=
eith.warren@ncsu.edu>=3B To: tap-l@lists.ncsu.edu>=3B Subject: =
Re: [tap-l] Tin Foil Capacitor>=3B Date: Thu=2C 17 Feb 2011 16:59:50 =
-0500>=3B >=3B You are keeping your wires off of the table righ=
t? I have not tried this>=3B demo yet but I know from recent trouble=
shooting that normal lab wires will>=3B discharge an electroscope pr=
etty quick if they are lying on the lecture>=3B table. The coating i=
s not rated for such high voltages.>=3B >=3B -Keith>=3B n=
csu>=3B >=3B -----Original Message----->=3B From: tap-l-o=
wner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On>=3B Behalf=
Of Paul Nord>=3B Sent: Thursday=2C February 17=2C 2011 4:41 PM&g=
t=3B To: tap-l@lists.ncsu.edu>=3B Cc: Paul Nord>=3B Subject: Re=
: [tap-l] Tin Foil Capacitor>=3B >=3B Dale=2C>=3B >=
=3B You should have tried it last week. Much too warm today. You probably=
need>=3B to be quick or do this with very low humidity.>=3B >=3B There were a couple of things said in that article that confused m=
e.>=3B Perhaps the experts can shed some light on this. In the last =
paragraph the>=3B author mentioned that this effect wouldn't work if =
you had insulating layers>=3B between the rolls of foil. Though he s=
eems to imply that he has not tried>=3B this. Would a coil of a sing=
le foil with a insulating layer have a higher>=3B capacitance than a =
conducting tube? Wouldn't the charge simply move to the>=3B outside =
surface?>=3B >=3B Second point of confusion. The entire demons=
tration is intended to infer>=3B that a charged rod has a lower capac=
itance than a flat sheet. Yet the>=3B author suggests that this woul=
d not work if the foil were wrapped on a>=3B conducting rod. Or was =
he only intending to say that this wouldn't work if>=3B the rod were =
grounded?>=3B >=3B Paul>=3B >=3B On Feb 17=2C 2011=
=2C at 3:24 PM=2C Dale E. Stille wrote:>=3B >=3B >=3B Tappers=
=2C>=3B >=3B >=3B >=3B Anybody do the "Tin Foil Capacitor" =
demo by Frank Noschese that was>=3B mentioned on page 621 of the Dec.=
2010 TPT. Basically you have a roll of>=3B tin foil connected to a =
electroscope. When you charge the electroscope and>=3B then unroll t=
he tin foil the voltage goes down=2C and when you roll it back up>=3B=
the voltage returns to the original value.>=3B >=3B My problem whe=
n I try to set this up is the voltage leaks off this at>=3B about 100=
0 V. per minute which make it unusable for me. I have narrowed it>=
=3B down to the fact that the voltage is leaking directly off the tin foil.=
I>=3B imagine there is some trick to making this work like the vide=
o that went>=3B along with the article but I ain't catching it.&g=
t=3B >=3B Can somebody clue me in??>=3B >=3B >=3B >=3B Th=
anks=2C>=3B >=3B Dale>=3B >=3B >=3B >=3B &g=
t=3B
=

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From tap-l-owner@lists.ncsu.edu Fri Feb 18 09:43:20 2011

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