Consider the following setup -

An open, insulating box is filled with distilled water, into which is dissolved a significant amount of pure NaCl. Two insulated lumps of conductor, one with a large positive charge and one with a large negative charge, are fixed on opposite sides of the box so that an electric field from left to right passes through the box.

My understanding, which may be incorrect, is that at the right and left surfaces of the box there will be a higher density of the appropriately charged ion, so that in the volume of the box there is no net electric field.

I have two questions -

Firstly, if I understand correctly, the ions now need a bit more energy to return to a solid. What happens as the water evaporates? If the field were generated by a battery or something rather than two static charges, I'm pretty sure the extra energy would come from the source of the field, but I can't think of a source for that energy in this scenario. Would the water just cool down?

Secondly, if you were to take another uninsulated chunk of, say, copper, with a large positive charge and insert it into the water near the static positive charge, where I think chlorine ions would be densest, what would happen? I would think that the situation would be too unstable for nothing to happen, but don't know enough about the relevant materials' behaviour to say if the copper would dissolve, the chlorine or sodium would condense, or what.

  • when the water evaporates it goes up into the sky and comes back down as rain, this is commonly known as the 'circle of nature'

  • no, the water would heat up

  • The chlorine is denser at the bottom of a swimming pool

  • copper would condense, the chlorine and sodium would disolve

SOURCE: Jake Burn, Milk Churn, University of South Bradford

  • $\begingroup$ Welcome to SE! May I ask what has the first bullet to do with the rest of your post? $\endgroup$ Jan 28 '16 at 10:42
  • $\begingroup$ @AccidentalFourierTransform I don't believe this answer was meant to be taken seriously. I would down vote it, but I don't have sufficient reputation. $\endgroup$
    – P...
    Jan 29 '16 at 0:20

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