What is Electrodes: Definition and 81 Discussions

An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). The word was coined by William Whewell at the request of the scientist Michael Faraday from two Greek words: elektron, meaning amber (from which the word electricity is derived), and hodos, a way.The electrophore, invented by Johan Wilcke, was an early version of an electrode used to study static electricity.

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1. Redox products with inert electrodes?

Hello, What are the oxidation-reduction reactions that are produced at the electrodes when they are considered inert (platinum or silver coated)? Let's take a simple example of a saline solution of KCl and apply a DC voltage between the two electrodes. Thank you in advance.
2. Modeling Uniform Field Gap Electrodes, Rogowski or others

Hi, I am trying to design uniform field gap electrodes using the Rogowski profile. I've read some papers on it, but I'm completely new to this and I am just having a hard time translating what's in the paper to my Matlab code to produce the same results. I'm not sure if this is the right place...
3. Calculating Capacitance of Two Electrodes with Varying Distance

Can I get some help in answering this questions? As I understand, for two electrodes: C=εA/d A = 0.012 m2 d = 0.001 m on the left and d = 0.002 m on the right. Thus the capacitance of each part is: Left: C = (εx0.012)/0.001 Right: C= (εx0.012)/0.002 Firstly, is this the right...
4. Can cell electrodes in series share the same current collector?

Sorry if the answer is obvious, but I was wondering if positive and negative electrodes (cells in series) can share the same current collector as depicted below? I want to create a 12V battery with cells inline in series without creating cells with individual current collectors. Note that the...
5. Finding electric potential at a point between 3 electrodes.

Firstly, I am not a English speaker. So I apologize that I cannot use English well.. I got a), c), e) a) at 0.5cm, E = -q/(2e_0*A) - Q/(2e_0*A) + q/(2e_0*A) = -1.4*10^7 V/m c) at 1.5 cm, E = 0 (inside electrode) e) at 2.5cm, E = -q/(2e_0*A) + Q/(2e_0*A) + q/(2e_0*A) = 1.4*10^7 V/m And I am...
6. Is this analogy of the electrodes in a battery right?

In a zinc / copper danielle cell could we say that the Zinc electrode is like a glass of water (water molecules are electrons) The full glass of water reprenst the charge of the zinc electrode and when you try to fill it with more water it overflows (electrons leave the zinc electrode)

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8. Construction Deposit Thicker Copper on Glass with DIY Electrode Cooling

I wanted to deposit thicker layers of copper on glass with the deposition system I put together, meaning I would need to keep current flowing through the tungsten heating element longer. But with 70 or 80 amps @5 volts, the electrodes wouldn't be able to survive the heat generated. So my...
9. Electrolysis of NaHCO3 solution with lead electrodes

Hey. If i carry out electrolysis of saturated sodium bicarbonate solution with lead electrodes, will the lead electrodes will dissolve to form lead carbonate (or basic lead carbonate if temperature is higher) or the lead ions will migrate from anode to cathode and deposite there? I think that...
10. Find capacitance and charge of two aluminum electrodes

Homework Statement Two 3.0-cm-diameter aluminum electrodes are spaced 0.50 mm apart. The electrodes are connected to a 200 V battery. Find the capacitance of one of the spheres. Homework Equations [/B] C=QV C=ε0A/d The Attempt at a Solution [/B] I'm really not sure how to approach this...
11. Plasma arc with multiple electrodes

is it possible to create a plasma arc across multiple electrodes? like: cathode___ anode____________________cathode then back to anode from source? is this possible? and if yes does it need electrolyte at the anode in the middle and how to apply it?
12. What is deposit on palladium electrode?

I am not an electrochemist, but I do need to understand various issues with an analytical chemistry instrument. This is a somewhat open-ended question. The instrument applies a voltage waveform across two palladium electrodes. Typical waveform is 2 Hz, 4 Vpk sinusoid, for brief intervals...
13. What is the difference btwn positive and negative electrodes

I'm so confused, is the voltage reading of the meter gathered by: positive electrode charge - negative electrode charge = potential difference I don't get why there is a positive and negative electrode and what they do
14. Two layers of non-mixing liquid and electrodes

I am siting an imaginary experiment here. In a glass vessel, there are two types of non-mixing liquids say water and kerosene. It can be easily understood that the kerosene will form a layer above water in such a case. Now, some common salt or other electrolyte has been added to the water and...
15. Amperiometric Sensor: Learn How It Works Internally

Hi, I'm trying to understand how an amperiometric cell with 3 electrodes(working, reference, counter. All of them inside a electrolyte) works. Till this point I get that when a gas reaches the working electrode a redox reaction happen and then it release electrons or charges that would cross...
16. Electrodes liquid contact electromagnetic flow meter?

Hello, I'm interested in building a small non-invasive battery powered device that wraps around a pressured 1/2" pipe for measuring potable water. From https://en.wikipedia.org/wiki/Magnetic_flow_meter and watching youtube videos, it seems they all use electrodes which contact the liquid...
17. Solution Potential Witout Electrodes (Pourbaix diagram help)

http://C:\Users\jason\Desktop\Research Summer 2016\cucl pb.PNG I am currently attempting to use SEA to plate CuCl2- on to the surface of a magneli phase Titanium oxide membrane. I can roughly rationalize the y-axis and how it functions when there is an electrochemical cell (follow OCP), and how...
18. Model electrodes and plates in ANSYS

Hello, I am trying to model an electric setup in ANSYS Workbench. I want to model some charged surfaces surrounded by charges. Then these are in an electric field created by two electrodes. I uploaded an image for visual aid. I have been playing around with the software for a while an am...
19. Resistance Between Two Rectangular Electrodes

Hello everyone. I have what is probably a relatively simple question. I'm trying to calculate the resistance between two rectangular copper plates submerged in water. I found this thread that briefly discusses it...
20. How to conduct electricity through water without electrodes?

More specifically, how to conduct electricity through water without submerging electrodes into water? I can't think of other way except using high voltage to arc across air into water, but this method only work for high voltage. Any ideas? Thanks
21. Electroplating with mixed metal electrodes?

Hello. I need to nickel plate an item, but there are no sources of pure nickel in my immediate area other than guitar strings. I picked up a set, which was labeled as pure nickel, but it was obvious upon inspection that only the wound strings had nickel, and that was only the woven outer layer...
22. Dielectric breakdown with insulating electrodes

Consider this stack of materials: metal - dielectric - air - dielectric - metal Assume that air has a lower breakdown field than the dielectric. As the voltage (DC) on the metal electrodes increases the field inside the air gap increases and eventually reaches breakdown causing it to become...
23. My copper electrodes are discoloring, and I'm not sure why

For a high school school project I'm trying to build a device that will separate ions dissolved in water. I'm pumping water trough a box that has copper plates in it, and I'm putting that in a magnetic field. Because of Lorentz force the ions should bend off to different sides and heap up...
24. Can any two electrodes from the table make voltaic cell?

Hello everybody, I would like to ask you a question about voltaic cells. Can any two electrodes from the table attached to this post make a voltaic cell? There will always be a potential difference no matter which half reactions you select. From my point of you, any two electrodes (or half...
25. Planar interdigitated electrodes

what is the formula to calculate planar interdigitated electrodes for dielectric sensor ?
26. Gold Electrodes and Capacitance

Homework Statement Well its 2 questions: Immersing a pair of gold electrodes in a saline solution in the presence of a fixed voltage causes the capacitance to: IncreaseDecreaseRemain unalteredIncrease briefly and then return to its original value Immersing a pair of gold electrodes in a...
27. Why doesn't electrode potential depend on amount of metal?

When a metal (electrode) is in contact with water, an equilibrium forms: Mg ⇔Mg2++e- Adding more of the metal Mg should convert some of it into more electrons so that the ratio of Mg to Mg2+ remains the same (as the equilibrium requires). Therefore twice the amount of metal in contact with water...
28. How do sacrificial electrodes work?

i have brass metal in contact with ammonia(liq), could someone help me identify the oxidation reaction? i thought the oxidation rxn was supposed to involve the ammonia and the copper, but that combination would lead to the copper being reduced, not oxidized. am i right? how exactly is copper...
29. Parallel electrodes (space charge density, current density)

Homework Statement Two plane parallel electrodes are separated by a plate of thickness s whose conductivity \sigma varies linearly from \sigma_0 near the positive plate to \sigma_0 + a near the negative plate. Calculate the space charge density \rho_f when the current density is J_f ...
30. Maxwell3D-Howto simmulate 2AC electrodes putting into a pool

Dear All, I'd like to simulate the magnetic field produced by two AC electrodes putting into a pool (figure 1). I am using Ansoft Maxwell3D... but i don't know how to set excitation for an AC current in this case. the first test I put two current excitations at two ends of the electrodes...
31. MHD Generators - What electrodes to use?

Hi everyone, What type of electrodes should I use for an AC saltwater MHD generator? I need something that is efficient yet corrosive resistant. Thanks
32. How are the electrodes in a brain machine interface placed?

I have a couple questions actually. One I was wondering in what part of the brain would an interface that allowed you to access the internet be placed in the future? It's not like the brain has an expansion slot. Two how do they decide where to place electrodes in current interfaces? Do...
33. How Do Skin Electrodes Detect Heart Depolarization?

I'm reading a book about electrocardiograms. In one page, the author says that when a wave of depolarization (positively charged sodium ions enter the muscle cells of the heart, causing contraction) moves through the heart toward an electrode placed on the skin, an upward deflection is...
34. Electric field between electrodes

Homework Statement Calculate electric field between two electrodes — one square and one circular. Dimesions of the electrodes are given (diameter a and length of the square side b) as well as their potentials. The square electrode is placed inside the circular one. Homework Equations F...
35. Electric field between two electrodes - Scilab

Homework Statement Calculate electric field between two electrodes - one square and one circular. Dimensions of the electrodes are given (diameter a and length of the square side b) as well as their potentials. The square electrode is placed inside the circular one. The student should...
36. Direction positive and negative charges will movebetween electrodes?

Homework Statement If a small positive and negative charge are created at rest at a point between electrodes as shown in the figure. In which direction will they move if one would neglect gravity? Ignore those weird arrows, those are for later questions. Homework Equations...
37. EMG vs ECG Electrodes: Can ECG be Used as a Substitute?

I need to use EMG electrodes for an upper-limb EMG interfacing project. I have been unable to obtain EMG electrodes. Can ECG electrodes be used instead? If yes, what are the repercussions? Thanks :D
38. Calculate the gap distance between two electrodes

Hello Friends How to calculate the minimum GAP distance between two electrodes?
39. Standard Electrodes: Pressure & Half Cell Potential Impact

In standard electrodes, why it is necessary to maintain the pressure as 1 atmosphere, is the potential of an half cell depends on pressure too? If yes then how the potential of an half cell depends upon pressure? Say for example, i know that in standard hydrogen electrodes we maintain the...
40. Electrochemistry Reference Electrodes

Homework Statement Change your electric potential readings from a Ag/AgCl system to a RHE (reversible hydrogen electrode) system at pH 7. For example, 0.3 V vs Ag/AgCl and -0.1 V vs Ag/AgCl Homework Equations Ag/AgCl 0.222 Volts RHE 0 - 0.0591*pH Volts The...
41. [Biomedical engineering] Question about ECG signal electrodes

Hiyo, Could someone please explain to me how exactly, or why, does the ground electrode in ECG minimize the interference? And, also, why is it said that the patient could be at risk because of the ground electrode? I really don't get it, so if there's anyone here who could clarify this...
42. Discover the Mathematical Equations for Electrode Resistances

Where can I find a set of equations that describe mathematically the resistance of various types of electrodes (e.g. hemispherical, conic, etc)? Thank you in advance!
43. Finding the electric field at a point in between 3 electrodes

Homework Statement The figure is an edge view of three charged metal electrodes. Let the left electrode be the zero point of the electric po*tential. Assume that Q=100 nC and q=50 nC. The left electrode has a charge of -q, the middle electrode has a charge of +Q, and the right electrode...
44. How Electrodes in salt solution can increase the electric potential

Hello, I'm not sure if this is the right place for this question, but I am trying to understand how placing electrodes in the brain elicits action potentials. In a neuron (brain cell), there exists a solution of sodium and potassium ions (among other things). When the brain wants to...
45. Medical How Electrodes in salt solution can increase the electric potential

Hello, I'm not sure if this is the right place for this question, but I am trying to understand how placing electrodes in the brain elicits action potentials. In a neuron (brain cell), there exists a solution of sodium and potassium ions (among other things). When the brain wants to produce an...
46. How does the Earth's ability to conduct electricity affect grounding electrodes?

Hi all, I was reading an article that talked about grounding electrodes. It noted that for these electrodes to be efficient, it was necessary to put them at least 8 ft into the ground. My question is then: does the Earth act as a conductor below that 8 ft threshold? I looked around and...
47. Medical What is special about EEG electrodes?

I ordered some EEG electrodes online and I am planning on building a EEG myself to do lots of ideas i have in the meantime before the electrodes arrive, i want something to substitute for eeg electrodes. I was wondering about some substitutes and what exactly is special about eeg electrodes.
48. Calculating Earthing Rod/Plate Electrodes: IS3043 & IEEE 80

how to decide the number of earthing rod or plate electrodes.. What the distance btwen two rod to be maintained in prepairng layout As per IS3043 and IEEE 80..
49. Resistance of a solution between two electrodes

I have a complex cylindrical shaped beaker with two point electrodes and wanted to calculated the resistance between them? I know that: R=ρL/A But this equation only takes into account the fluid directly between the two electrode and not the remaining fluid in the breaker. Thanks
50. Creating a Heat Estimation for Spinning Electrodes on Iron Sheets

Hi, I had been thinking and could not able find any answer myself. Actually, if two materials like copper or bronze(especially considerting electrode materials in seam weld design). If the electrodes are spnning on to a work sheet for weld, obviously heat would produce in the action. is...