Re: Electroscope Materials
- From: Jeff Liebermann <jeffl@xxxxxxxxxx>
- Date: Sat, 21 Jun 2008 19:11:39 -0700
On Sat, 21 Jun 2008 17:49:24 -0700, Jeff Liebermann <jeffl@xxxxxxxxxx>
wrote:
On Sat, 21 Jun 2008 20:49:59 +0100, "christofire"
<christofire@xxxxxxxxxxxxxx> wrote:
"Jeff Liebermann" <jeffl@xxxxxxxxxx> wrote in message
news:6ptn54156eh5n6g67kt4aqim2d84hblqhs@xxxxxxxxxx
On Fri, 20 Jun 2008 12:36:29 -0500, "amdx" <amdx@xxxxxxxxxxx> wrote:
Aluminum is MUCH
easier to handle than gold, but because it weighs more, is less sensitive.
Huh? Aluminium weighs more than gold? Am I in the wrong universe?
I said weight, not specific gravity or density. Hammered gold leaf is
about 0.1 micro meters thick. Aluminum foil that thin would just
crumble or shred itself. I think the best I can find for aluminum
foil is rolled (not hammered) at about 1,000 micro meters thick.
That's about 10,000 times as thick as gold.
The electrostatic forces on each leaf are repelling each other, but
are also fighting gravity. The flexibility and weight of the material
is a key part of how much they move and thus their sensitivity.
<http://en.wikipedia.org/wiki/Electrometer>
I errrrred. 1,000 micrometers is about the thickness of the paper
backed aluminum foil on the gum wrappers. It is possible to buy pure
aluminum leaf down to about 15 micro meters thickness. That would get
the weight down to something comparable to gold. However, there's a
problem. The aluminum leaf is substantially stiffer than the gold
version, thus reducing its sensitivity. Aluminum leaf will certainly
work (I haven't tried it), but gold is probably better.
<http://www.theodoregray.com/PeriodicTable/Elements/LeafGroup/index.s7.html>
I got some email asking what keeps the two leafs of the electroscope
from sticking to each other permanently? There two leafs are part of
a single conductor. In order for them to stick, it would be necessary
to have opposite charges on each leaf, which is impossible. There's
always a small surface electrostatic charge to keep them slightly
apart and prevent welding. However, if the two leafs were insulated
from each other, welding would certainly be a problem.
Don't ask me where to find the red squirrels used to make the gilders
brushes.
Fizzix lecture on electroscope (9 mins):
<http://www.youtube.com/watch?v=5j4piAI_igE>
Note that the electroscope in the video deflects when the charged
plastic gets within about 2 cm of the top electrode. The one we built
in college would detect a similar piece of plastic at about 0.5 meter
and a balloon at about 3 meters. Ambient radioactivity and cosmic
rays were a measurable source of error. Sorry, no photos.
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 jeffl@xxxxxxxxxxxxxxxxxxxxxx
# http://802.11junk.com jeffl@xxxxxxxxxx
# http://www.LearnByDestroying.com AE6KS
.
- References:
- Electroscope Materials
- From: amdx
- Re: Electroscope Materials
- From: Jeff Liebermann
- Re: Electroscope Materials
- From: christofire
- Re: Electroscope Materials
- From: Jeff Liebermann
- Electroscope Materials
- Prev by Date: Re: Darwin awards, maybe, too soon to tell
- Next by Date: Re: OT: Post Turtle
- Previous by thread: Re: Electroscope Materials
- Next by thread: FT: So, all Osama needs to do to get a B61 nuke is to poison the dog?
- Index(es):
Relevant Pages
|
