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Re: First EM lab



on 13/1/02 4:36 PM, Herbert H Gottlieb at herbgottlieb@JUNO.COM wrote:

On Sat, 12 Jan 2002 21:59:12 -0500 Joe Heafner <heafnerj@VNET.NET>
writes:

Take a plastic ball point pen and rub it in your hair so that it
acquires a net charge. Hold it a couple of centimeters above a small
piece of paper (e.g. a tiny bit of paper from a notebook sheet).
Find the height at which the paper is just lifted by the electric
force. From this, estimate the polarizibility of carbon.

I don't get is Joe. I tried what you said
and found that the height distance is EXACTLY 3.28759
centimeters. Using this data how do I estimate the
polarizibility of carbon??

Maybe it would be better to use an ordinary wood pencil
that has some hardened CARBON inside?

There are plenty of carbon atoms in the paper, Herb.

The interesting situation that Joe has put forward comes from Chabey and
Sherwood's text he refers to. It's a homework problem there.

An estimate is needed of the charge on the pen; this estimate will be based
on hands-on homework done earlier by the student with charged (sticky) tape.

Brian McInnes