Gold Electrodes and Capacitance

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SUMMARY

Immersing a pair of gold electrodes in a saline solution with a fixed voltage increases the capacitance due to the saline acting as a dielectric, which has a higher relative permittivity than air. The charge storage capability of the electrodes increases as the dielectric polarizes, leading to a higher capacitance. Regarding current, since the voltage remains fixed, the current should remain unaltered, despite the presence of saline, unless electrolysis occurs, which can change the dynamics at the electrodes.

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  • Understanding of capacitor behavior and capacitance principles
  • Knowledge of dielectric materials and their effects on capacitance
  • Familiarity with basic electrolysis concepts
  • Experience with Ohm's Law and its application to current and voltage relationships
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  • Research the effects of different dielectric materials on capacitance
  • Study the principles of electrolysis and its impact on current flow
  • Learn about the relationship between voltage, current, and resistance in circuits
  • Explore the behavior of capacitors in varying environmental conditions
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OHMy..G.Simon?
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Homework Statement


Well its 2 questions:
  1. Immersing a pair of gold electrodes in a saline solution in the presence of a fixed voltage causes the capacitance to:
    1. Increase
    2. Decrease
    3. Remain unaltered
    4. Increase briefly and then return to its original value
  2. Immersing a pair of gold electrodes in a saline solution in the presence of a fixed voltage causes the Current to: (same answers as above)

Homework Equations




The Attempt at a Solution


I have been racking my brain over this for the last several hours. It was supposed to be made clear in a practical class that ended up having faulty equipment, but i digress...

I basically began with the idea that the parallel plates would act as capacitors and when they were submerged in saline, it would act as the dielectric (higher relative dielectric than air). Given the fixed voltage, this would increase the charge that would be able to be stored by polarising the dielectric and reducing the electric field? (Am I at least on the right track here?) So i concluded that the capacitance would increase.

The second question is the one that is giving me real trouble. I can't find any association between capacitance and current and I definitely don't understand how immersing gold electrodes in saline would change the current. The only thing I could come up with is the fact that the voltage is again fixed and given that voltage is proportional to current, would it be correct to say that the current shouldn't change? Or does the saline affect this?

I was reading about how one electrode is - and the other is + and how the electrons are both being attracted by the protons and repelled by the potential voltage and so in a capacitor there is a point where there is no net charge movement because the forces are equal?? Again this was just something that kind of made sense.

At this point I'm thinking that current would remain unaltered.

Help would be much appreciated, Thanks
 
Physics news on Phys.org
Inserting electrodes with a voltage into a saline solution changes it into an electrolysis setup.
Since the voltage is kept fixed the question then becomes what happens to the charge at the electrodes.
 
Last edited:
Ahh okay that makes much more sense now. Thanks for the help.
 

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