Re: Electric Field Mapping

["John S. Denker" <jsd@MONMOUTH.COM>]

Tina Fanetti wrote:

> I used the conducting silver ink on black conductive paper. I had the
>  positive lead on the point charge and the negative lead on the ring.

1) Newly-applied silver paint takes a while to
dry.  It gets more conductive as it dries.

2) Maybe you've got Brand-X silver paint with
not enough silver in it.

3) Sometimes it's easier to make a problem go away
than it is to understand the problem.  In this case,
I would just lay down a fine metal wire and then
slather it with silver paint to make the connection
to the paper.

That's not much work, and removes all sorts of
uncertainty.

4a) If OTOH you want to understand the situation,
take a piece of glass or regular non-conductive
paper, lay down some lines of silver paint, and
measure their resistance.

> I know there was good contact.

4b) Use four-point probe techniques to measure
resistance if there's every any question about
the contacts.

http://www.users.qwest.net/~csconductor/Experiment_Guide/Four%20Point%20Probe.htm