🚀 go-pugleaf

In article <1992Dec18.234928.16107@sfu.ca> palmer@sfu.ca (Leigh Palmer) writes:
>To this day I do not know why one end of that rod was etched, but I do
>know that I was rubbing the wrong end! My best guess is that the end is
>etched so that the *knowledgeable* physicist will always pick it up by
>that end, so as not to soil and render less effective the *other* end,
>which, as you've probably guessed, electrifies like gangbusters when
>clean and rubbed with the silk cloth.

My guess is your guess is correct.

Triboelectrification works purely by contact.  The function
of rubbing is to bring more "virgin" material into contact.
Because the two materials are insulators (find me two that
aren't and are still good for demos of triboelectrification),
you can't simply place them together and incant olde english;
you need to deform the silk fibers, rotating their large
total surface to the face of the cloth, and rub them
maximally around on the surface of the glass.

As you might imagine, etched glass has very little readily
available surface area, even though it would have fractally
much more total surface area.

I think in addition to the anti-oil argument, it's just
plain easier for rickety old physics lecturers to hang on
to the etched end than the smooth end.

Maybe if you'd been a bit more ancient yourself...

				--Blair
				  "Polystyrene peanuts are an absolute gas."