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Making electric field in water

Discussion in 'General Electronics' started by Ginm, Feb 3, 2004.

  1. Ginm

    Ginm Guest

    This is partly related to chemistry (any electrochemists in here?): I
    have a chemistry project to do and I need to setup a low-voltage
    electric field for a beaker of water (about 300mL, maybe less)

    So here is my initial proposition: Attach a power source (household
    battery) to two electrodes (strip of copper or any other good
    conducting metal) with two wires (copper, most likely) and submerge
    in the beaker of water.

    I also want to be able to measure the voltage between these two
    electrodes, so where and how would I attach a voltmeter to this
    apparatus?

    And are there any problems with the above setup? Or any suggestions
    for improvements?

    All help is greatly appreciated!
     
  2. Robert Baer

    Robert Baer Guest

    By "household" battery, you could be referring to a 1.5V flashlight
    cell or a 9V battery - both relatively common in most households.
    Just connect the voltmeter across the battery; why this is needed i
    cannot imagine.
    Water....from where?
    From most taps, the water is relatively conductive as compared to
    De-ionized or distilled water.
    Exactly what do you want to observe or achieve?
    Produce hydrogen at one electrode and oxygen at the other?
    Let the water clean the electrodes?
    Sit there and look purty?
     
  3. Ginm

    Ginm Guest

    I will use distilled water, and the objective of the experiment is to
    see how an electric field would affect a property of water. I've
    found out after some research that water's dielectric constant would
    be decreased which means its solubility properties.

    A post in the electronics section said that it is not possible to
    creat an electric field in water without some sort of electrolysis.
     
  4. Robert Baer

    Robert Baer Guest

    One can create an electric field in *any* insulator or dielectric by
    the simple procedure of placing said dielectric between two plates and
    then applyiong an electric potential between those plates.
    It is part of one of the simple definitions and construction aspects
    of capacitors.
    So the "need" for an electrolyte is bull and a good way to destroy
    those aspects that you wish to investigate.
    The voltmeter will only confirm that you have such-and-such a
    potential between theterminals, and give you a vew more digits of
    accuracy.
    You should construct flat plates of known (same) size with a means of
    keeping them parallel and adjusting (and measuring) their seperation.
    One can calculate the capacitance if the assembly was in vacuo or in
    air or in pure water as references.
    Your statement implies that the dielectric constant of water is not
    constant - that it alters with anapplied field.
    So, one needs to use a capacitance meter, to determine that aspect,
    and a method of varying the applied voltage from zero to some value (as
    well as adjusting the plate seperation).
    And/or, one needs to devise a method to measure the solubility of
    something in water on a semi-real time basis as the electric field is
    varied.

    Remember, the capacitance meter will alter the applied electric field
    (evenof that was zero), and so will have an effect that can alter the
    results if the presumption is correct.
    Ditto on adding solutes.
     
  5. =---

    Unless you use pure destillated water, you will have some current flow
    through it. The moment you solve something in pure water, it's not pure
    anymore so you will find some current flowing. Unless you want the
    electrolysis you can prevent this by carefully insulating the electrodes. In
    both situations you can simply measure the voltage with a voltmeter. I
    predict it will be the same as the battery voltage.

    petrus
     
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