Electric Deflection of Water Columns

[brian whatcott <inet@intellisys.net>]

At 14:26 2/20/98 -0500, John Gastineau wrote:
> ... charged tape is attracted to objects that are electrically neutral.
> There is a force of attraction between a charged object and an
> uncharged dielectric. We see this experimentally. 
....
> The electric field of the tape induces a polarization in the
> dielectric. The electric field from the tape is far from uniform.
> Because of the polarization of the dielectric, the dipoles do feel a
> net force in the inhomogeneous field. (to be specific, suppose we have
> a negatively charged tape. The polarization means that a small (very
> small) charge separation is induced in the dielectric, and the negative
> charges are, on the whole, farther from the tape than the positive
> charges. The repulsive force on the negative charges is less than the
> attractive force on the positive charges, and we have a net attractive
> force.
>
> JEG

After demonstrating the appreciable deflection of a thread of water in an
inhomogeneous electric field, it would be interesting to consider the
effect of providing ( as far as one possibly can) a uniform transverse
electric field. 

The high dielectric constant of water renders this field distorted in the
region of the water thread of course. But let us suppose that there is an
appreciable torque turning the water around a vertical axis. I wonder what
would be the simplest experimental method of demonstrating this effect?
 Perhaps a low-friction splash plate which is able to revolve around a
vertical axis and to which the water transfers its angular momentum?

Come to think of it, the principle of electrostatic deflection of water (or
rather ink ) has been in use for many years commercially.
 And I cannot remember special precautions to make the field especially
non-uniform. Ah yes - the ink droplets are customarily charged - so the
uniformity of the field is not material in this particular case, I suppose....

Whatcott