Date: Thu Feb 8 10:53:31 2007

Author: Jerry DiMarco

Subject: Re: dipole

Here is what I think is happening. The straw is initially drawn to
one plate by induction. As it nears, charge begins to leak off the straw
because the end is like a point. The charge leakage reduces the inductive
attraction, and the straw stops short of the plate in an equilibrium
position. When you stop cranking the Wimshurst, the charge on the plates
start dropping. When it drops below the threshold voltage where the plate
can draw charge off the straw, the straw is drawn closer to the plate,
again by inductive attraction, and touches it. This could perhaps be
tested by cranking the Wimshurst much slower to keep the voltage below the
threshold level. If that proves difficult, maybe a variable HV supply
would be better...


At 06:31 PM 2/7/2007, you wrote:
>... To answer Ziggy's/Adam's questions - the straw does not oscillate as
>far as I can tell by standing close, and it never touches the plate that
>it's near. As the Whimshurst slows, the straw actually touches the nearest
>plate before being repelled to the other plate. That's when this thing
>behaves normally.