Message-Id: <v01540b0faf2abc18fdd2@[192.174.2.173]>
Date: Fri, 14 Feb 1997 17:05:00 -0800
To: pinhole@exploratorium.edu
From: pauld@exploratorium.edu (Paul Doherty)
Subject: electrostatics
Date: Thu, 13 Feb 1997 21:32:28 -0500 (EST)
From: Biedenweg@aol.com
To: pauld@exploratorium.edu
Subject: electrostatics and magnetism
Paul, I called a couple of people that repair and/or work on electronic
balances including the Ohaus company scale rep. They all told me that putting
magnets on the scales would not harm them. Although they may cause the scales
with force transducers in them to give false readings. I have the names and
numbers of these people if you would like them.
I also collected repulsion data last night and would like to know what you
think of them. I set a magnet on the scale and repelled it with a magnet
taped to the bottom of a meter stick. I kept this meter stick stack of
magnets level using a bubble leveller. The data I got with the scale tared
were
distance apart followed by scale reading (16 cm, .08gm; 8 cm, 1.09gm; 5.33
cm, 4.55 gm; 4 cm,10.43 gm; 2 cm, 67.8 gm). I'm not sure what kind of
function gives the best fit for these data, but do they basically agree with
what you have found. Do you have a reference for the 1/r to the fourth power
logic? I understand the logic as you explained it, but have never heard this
before.
Magnetism additional question- I am beginning to play around with sprinkling
iron filings in a sealed Petri dish and trying to look at magnetic fields
around a magnet. My preliminary studies show that it is a lot tougher to get
nice field shapes than books indicate. Do you know how to do this easily?
(that is do you know how to use iron filings or photocopy developer to show
nice magnetic field lines around magnets?
Electrostatics- I just went to an insulation company and got some polystyrene
sheets from them. One is a 3" foam sheet made of little cells of foam; the
other is a blue foam sheet 2" thickness of extruded polystyrene. I could have
gotten white extruded polystyerene, but they called this artboard and it was
$104 for a 2' X 8' sheet. Are the two sheets that I bought the same material
that you have had success with?
Final question-do you know a cheap source of piezo cigarette lighters. Do
they sell them at K-mart or Target or any place that you know? Thanks a
million. Doug Biedenweg