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PH, free charge, and flowing water

  1. May 21, 2004 #1
    Anybody got a relationship between fresh water PH level, and amount of + or - net charge, say per cubic meter of H20, at a nominal temperature. Rivers are usually alkaline, thefore have a net -charge, the cubic meters flowing at X meters/sec, and therefor function effectively as a fat wire. I would like to examine how much magnetic field is generated, naturally from this "conductor". Perhaps to be used for navigation.
  2. jcsd
  3. May 22, 2004 #2
    Still waiting It must be tough a question for you physics people i guess.
  4. May 22, 2004 #3


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    pH level gives you the concentration of [itex]H^{+}[/itex] or [itex]H_{3}O^{+}[/itex] ions. You can also find pOH from pH, and use that to find the concentration of the negative ions. Finding the difference between these two concentrations should give you a net charge concentration, I would think. I mean, if you [itex]5 \times 10^{-5} \mbox{ moles of }H^{+} \mbox { ions per Litre}[/itex] and [itex]6 \times 10^{-5} \mbox{ moles of }OH^{-} \mbox { ions per Litre}[/itex], and one mole of electrons has a charge of [itex]-9.64870\times 10^4 \ C[/itex] then you would have [itex]-0.964870\ C/L[/itex]. If it was flowing at [itex]\phi[/itex] L/second, then you would have an electric current of [itex]-0.964870\phi\ A[/itex]. The magentic field as a function of the distance, d, from the axis of current flow (the river), would be:

    [tex]B(d) = \frac{0.964870\mu_o \phi}{2\pi d}[/tex].
  5. May 23, 2004 #4


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    qnet = [ pH x (your age) - (flow rate) x (my social security number)] x sinπ ; rather than go through the computation, call it zero --- charge balance applies. Reread your intro chem texts. The coulombic energy required to pack one coulomb of "free charge" into a liter of river water is --- shall we say "large?" A river running at such charge density would be truly exciting to see --- at a safe distance --- say, from the next galaxy.
  6. May 24, 2004 #5
    Excellent, AKG. Thank You. Now by your calculations, say the missouri river, with a nominal pH of 8, yeilds -9.65e-2 C/l. The flow rate is variable, but 30,000 cft/s is a nominal number. This yeilds a net current of ~31000Amps. Any comments?

    On the wilder side now, any means of coupling some of the current out, over many miles, say using an equivalent of a current transformer? & would this action effect the net pH in the river?
  7. May 24, 2004 #6
    Hey, maybe we killed the "high amps" low voltage problem for Artic Fox, as well.
  8. May 24, 2004 #7
    Ions and Charge

    I think you guys may be mislead with the whole charge thing. pH is the negative log of the hydrogen (or technically hydronium) ion concentration. pH + pOH always equals 14 so in a neutral solution, both concentrations equal 10^-7. But the pH is varied by dissolving other compounds in water. Take, as a typical example, HCl. It is a strong acid, and so completely dissociates into H+ ions and Cl- ions. This raises the pH of the water, but there is no net charge on the water. In a river, the same thing happens, compounds get dissolved in the water and certain ones dissociate into ions that increase or decrease the concentration of H+ in the water. There is no exchange of charge here so the water isn't charged as far as I know.
  9. May 25, 2004 #8
    That makes alot of sense, who ever got "shocked" by water. I just got thrown off by the Mag-meter, fluid GPM meter. It has two magnets at say +90 and -90 degrees, and two electric probes at say 0 and 180 degrees. Any "conductive" liquid (ie, water with a pH other that 7), flowing in the system registers and electric voltage proportional to flow rate. Guess the magnetic field simply pushed the +ions right and the -ions left. And thus the voltage.
  10. May 25, 2004 #9
    BTW, I am still alittle confused about non-DI distilled water, with a PH other that 7. Is that due to minute amount of dissolved minerals?, And what about the water ionizers? (dubiously) sold as a health product, also just manipulate the inherient dissolved minerals in the water?
  11. May 25, 2004 #10
    , You think I wore out my welcome, But this uncle buck is here to stay. Now Lets push forward. Magnetic field, flowing water, and PH. Now we got electric voltage to boot, curtsy of the ""magnets in the stream bed. How far can we take this dreamers, or as it looks, sleepers.
  12. May 28, 2004 #11
    Uncle buck is dissapointed at you physics people. I thought that somebody shark would catch it, guess not. You get an F this go around, But I just gotta thank AKG and bystander for their outstanding previous brilliant.

    The voltage from the conductive fluid in the b-field is due to faradays law. Nothing to do with free charge in the water or the seperation of the flowing ions,

    ie. E = B X L X V

    whereas E = induced voltage

    B= magnetic field intensity

    L= distance between electrodes

    V= average flow velocity of conductive Liquid.

    But, you gotta admitt, 31,000 Amps of free flowing charge is pretty inviting, NO?
  13. Jun 1, 2004 #12
    Once again, we have a medium that can not support a charge, yet, produces and voltage (ie. potential), I get more confusous all the time, I am alone, nobody to help.
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