Re: measuring conductance

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From: Patrick Roisen (pershadow@sbcglobal.net)
Date: Thu Sep 04 2003 - 22:08:39 PDT 

Message-ID: <20030905050839.12333.qmail@web80101.mail.yahoo.com>
Date: Thu, 4 Sep 2003 22:08:39 -0700 (PDT)
From: Patrick Roisen <pershadow@sbcglobal.net>
Subject: Re: measuring conductance

If your biology teachers do biotechnology labs that
involve electrophoresis, many of the lab set ups for
this use a variable power supply that allows you to
switch between measuring the volts and amps of the
electrophoresis box. One of the labs that is done in
San Mateo county (supported by the Gene Connection
consortium; if you're in the Bay Area, check with your
Bio teachers to see if they know anything about BABEC
or other biotech consortiums, which would be able to
get the info from Gene Connection, or go to
www.geneconnection.com) uses the equipment to
illustrate Ohm's Law. With some changes, you could
use it. Basically, if you keep the voltage constant
and add 100 mL of whatever solution to the box that
otherwise has distilled water, the amps reading will
be proportional to the conductance of the solution.
There is another lab supported by Gene Connection that
is a series of labs where students use conductance to
discover some of the relationships between different
elements that help them understand how the periodic
table is put together.
An alternative is if any of the teachers at your
school has sensor probes like the Vernier Lab Pro.
Vernier make a $89 conductivity probe
(http://www.vernier.com/probes/probes.html?con-bta&template=standard.html)
that I've used to do diffusion labs, etc. I'm sure
other vendors sell similar sensors.

Hope this helps,
Pat Roisen

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