# Help me understand this video

Discussion in 'Electronic Design' started by amdx, Jan 31, 2013.

1. ### amdxGuest

Hi all,
At 3:35 of this video they move a water drop with an electric charge.
There are three electrodes, a black one that seems to be in constant
contact with the water drop through the continuous trace. Then there are
two red electrodes that I think are at the same potential.

That is my question, are the two red electrodes connected together?

This is an outcast in these NerdRage videos, He has 128 videos, so far
cool, nerdy stuff. I think many will enjoy them.
Mikek

2. ### brentGuest

I watched this. I am pretty sure the two red probes are the same
voltage. I had to really slow down and look at the shapes etched on
the glass. The black probe connects to one long continuous connection
and half the drop is always on that geometric shape. Along the long
rectangle (which the black probe connects to) are lots of little
squares. Each square floats relative to the other squares and the
long rectangle.

When she moves the red probe she is charging an adjacent square and
ltting the charge off the current square. The water drop then centers
itself on the newly charged square which causes the movement.

3. ### brentGuest

Nice to see Canadians let their science students build bombs. Have to
go to 5:25. Pretty cool.

4. ### Sylvia ElseGuest

It seems to me that the drop motion is in two stages. Firstly, when both
red probes are connected, the drop moves about halfway, then when one
probe is removed, the drop moves the rest of the way.

I note that she isn't taking any care to avoid having the probes touch,
which is consistent with the idea that they're at the same potential anyway.

Sylvia.

5. ### George HeroldGuest

Exploding fruit and vegatables are always a crowd pleaser. :^)

George H.