Re: First EM lab

[Herbert H Gottlieb <herbgottlieb@JUNO.COM>]

On Sun, 13 Jan 2002 00:05:24 -0800 Bernard Cleyet <anngeorg@PACBELL.NET>
writes:
> OK
> If the separation (dipole) is << distance (l) to the pen's charge
> (q) and it is concentrated (far field) the force is
>  ~ {2[Qd]*q / l^3} * 1 / 4pi*e   (Qd is the dipole moment) (SI > units)
>
> bc

 In that case, since I found that the height of the charged pen is
exactly 3.28159 centimeters (+/-  0.0002 rch), what is my percent error
for this EM lab exercise? Did I get a grade of A on this lab or should I
give up and drop the course now??

Herb

> Brian McInnes wrote:
>
> > 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


Herb Gottlieb from New York City
(Where it's nice to live but I wouldn't
want to be a tourist here)
herbgottlieb@juno.com