Re: Magnitude of feet-scuffing voltage?

[Ludwik Kowalski <kowalskiL@MAIL.MONTCLAIR.EDU>]

William Beaty wrote:
> Have any PHYS-L members studied the voltage of the human body WRT ground,
> when the human scuffs upon a rug during dry conditions?  What is the
> maximum voltage expected?  5KV?  10KV?  Does the size of the human make a
> big difference, or is there a "ceiling" of maximum voltage?
>
> Also, I'm looking for an electrometer which can display the body
> potential.  Might there exist an inexpensive "student electrometer" which
> will not be destroyed by contact with a charged person?  I've seen Pasco's
> ads, but theirs seems to only measure below 1KV.

Just an idea. Consider a beam of light going through a set of crossed
polarizers. Nearly nothing is going through. A Kerr cell is placed
between the polarizers and the H.V. is applied. The amount of light
passing now depends on the d.o.p. One electrode of the cell is grounded,
the other is connected to the object whose potential is measured with
respect to the ground. The signal from the photocell will be proportional
to the E^2 in the region traversed by light. This is not a typical
application of the Kerr effect but it may work for what you want.
You have to calibrate the system with a power supply.

Ludwik Kowalski