Electrodes sentence example
When we use platinum electrodes in acidulated water, hydrogen and oxygen are evolved.
In it the electrodes were of platinum and carbon.
The metals may be introduced into the arc in various ways, and in some cases where they can be obtained in sufficient quantity the metallic electrodes may be used in the place of carbon poles.
A third class of electric wave detector depends upon the power of electric oscillations to annul the electrolytic polarization of electrodes of small surface immersed in an electrolyte.
Duddell discovered in 1900 that if a continuous current carbon arc had its carbon electrodes connected by a condenser in series with an inductance, then under certain conditions oscillations were excited in this condenser circuit which appeared to be continuous.Advertisement
The electric arc is formed between cooled copper (positive) and carbon (negative) electrodes in an atmosphere of hydrogen or coal-gas.
Across the arc is a transverse or radial magnetic field, and the electrodes are connected by an oscillatory circuit consisting of a condenser and inductance.
He also found that, for the same current, the amount of chemical action was independent of the size of the electrodes and proportional to the time that the current flowed.
Since the electric forces are active throughout the whole solution, all the ions must come under its influence and therefore move, but their separation from the electrodes is determined by the electromotive force needed to liberate them.
When the ions are set free at the electrodes, they may unite with the substance of the electrode or with some constituent of the solution to form secondary products.Advertisement
At the electrodes, however, the small quantity of hydrogen and hydroxyl ions from the water are liberated first in cases where the ions of the salt have a higher decomposition voltage.
The obvious phenomena to be explained by any theory of electrolysis are the liberation of the products of chemical decomposition at the two electrodes while the intervening liquid is unaltered.
The tank is of porcelain or glazed earthenware, the electrodes for impure solutions are z in.
The Edison electric meter, like those of Sprague and Lane-Fox, was based upon the principle that when an electric current flows through an electrolyte, such as sulphate of copper or sulphate of zinc, the electrodes being plates of copper or zinc, metal is dissolved off one plate (the anode) and deposited on the other plate (the cathode).
The whole current supplied to the house flows through an electrolytic cell consisting of a glass tube containing two platinum electrodes; the electrolyte is dilute sulphuric acid covered with a thin layer of oil to prevent evaporation.Advertisement
The U-shaped electrolytic vessel and the electrodes are made of an alloy of platinum-iridium, the limbs of the tube being closed by stoppers made of fluor-spar, and fitted with two lateral exit tubes for carrying off the gases evolved.
The former includes electrodes, lamp carbons, &c. Coke, or some other form of amorphous carbon, is mixed with a little tar, and the required article moulded in a press or by a die.
The massive graphite is very easily machined and is widely used for electrodes, dynamo brushes, lead pencils and the like.
Count Gramont 5 has been able to obtain spectro scopic evidence of the metalloids in a mineral by employing powerful condensers and heating the electrodes in an oxyhydro gen flame when these (as is often the case) are not sufficiently conducting.
A battery with a sufficient number of cells is connected to these two electrodes so as to pass a current through the mercury vapour, negative electricity proceeding from the mercury cathode to the iron anode.Advertisement
This reverse electromotive force of polarization is produced in all electrolytes when the passage of the current changes the nature of the electrodes.
To explain these facts, Theodor Grotthus (1785-1822) in 1806 put forward an hypothesis which supposed that the opposite chemical constituents of an electrolyte interchanged partners all along the line between the electrodes when a current passed.
Interchanges must be supposed to go on whether a current passes or not, the function of the electric forces in electrolysis being merely to determine in what direction the parts of the molecules shall work their way through the liquid and to effect actual separation of these parts (or their secondary products) at the electrodes.
Hence there can be no reverse forces of polarization inside the liquid itself, such forces being confined to the surface of the electrodes.
If the ions move at equal rates, the salt which is decomposed to supply the ions liberated must be taken equally from the neighbourhood of the two electrodes.Advertisement
If we assume that no other cause is at work, it is easy to prove that, with non-dissolvable electrodes, the ratio of salt lost at the anode to the salt lost at the cathode must be equal to the ratio of the velocity of the cation to the velocity of the anion.
Hittorf and many other observers have made experiments to determine the unequal dilution of a solution round the two electrodes when a current passes.
If we eliminate the polarization at the electrodes, it can be shown that an electrolyte possesses a definite electric resistance and therefore a definite conductivity.
In order that the current should be maintained, and the electromotive force of the cell remain constant during action, it is necessary to ensure that the changes in the cell, chemical or other, which produce the current, should neither destroy the difference between the electrodes, nor coat either electrode with a non-conducting layer through which the current cannot pass.
But the internal rearrangements which accompany the production of a current do not cause any change in the original nature of the electrodes, fresh zinc being exposed at the anode, and copper being deposited on copper at the cathode.
In order that positively electrified ions may enter a solution, an equivalent amount of other positive ions must be removed or negative ions be added, and, for the process to occur spontaneously, the possible action at the two electrodes must involve a decrease in the total available energy of the system.
As stated above, an electromotive force is set up whenever there is a difference of any kind at two electrodes immersed in electrolytes.
Dolezalek, however, has attributed the difference to mechanical hindrances, which prevent the equalization of acid concentration in the neighbourhood of the electrodes, rather than to any essentially irreversible chemical action.
If we connect together in series a single Daniell's cell, a galvanometer, and two platinum electrodes dipping into acidulated water, no visible chemical decomposition ensues.
It seems that this reverse electromotive force of polarization is due to the deposit on the electrodes of minute quantities of the products of chemical decomposition.
Differences between the two electrodes are thus set up, and, as we have seen above, an electromotive force will therefore exist between them.
Sometimes the metal is deposited in a pulverulent form, at others as a firm tenacious film, the nature of the deposit being dependent upon the particular metal, the concentration of the solution, the difference of potential between the electrodes, and other experimental conditions.
Very irregular surfaces may require the use of specially shaped anodes in order that the distance between the electrodes may be fairly uniform, otherwise the portion of the cathode lying nearest to the anode may receive an undue share of the current, and therefore a greater thickness of coat.
When the two electrodes are ferro-magnetic, the direction of the current through the liquid is from the unmagnetized to the magnetized electrode, the latter being least attacked; with diamagnetic electrodes the reverse is the case.
They relate almost entirely to electrical phenomena, such as the magnetic rotation of light, the action of gas batteries, the effects of torsion on magnetism, the polarization of electrodes, &c., sufficiently complete accounts of which are given in Wiedemann's Galvanismus.
Several modifications were proposed, in one of which, intended for the heating of non-conducting substances, the electrodes were passed horizontally through perforations in the upper part of the crucible walls, and the charge in the lower part of the crucible was heated by radiation.
Horizontal channels were cut on opposite walls, through which the carbon poles or electrodes were passed into the upper part of the cavity.
Such a furnace, to take a current of 4 H.P. (say, of 60 amperes and so volts), measured externally about 6 by 6 by 7 in., and the electrodes were about o 4 in.
Many of the furnaces now in constant use depend mainly on this principle, a core of granular carbon fragments stamped together in the direct line between the electrodes, as in Acheson's carborundum furnace, being substituted for the carbon pencils.
The temperature of the electric furnace, whether of the arc or incandescence type, is practically limited to that at which the least easily vaporized material available for electrodes is converted into vapour.
Chaplet has patented a muffle or tube furnace, similar in principle, for use on a larger scale, with a number of electrodes placed above and below the muffle-tube.
A sheet iron case is then placed within the furnace, and the space between it and the walls rammed with limed charcoal; the interior is filled with fragments of the iron or copper to be alloyed, mixed with alumina and coarse charcoal, broken pieces of carbon being placed in position to connect the electrodes.
On passing a current of electricity, of which the volume and pressure are adjusted to the conditions of the electrolyte and electrodes, the anode slowly dissolves, leaving the insoluble impurities in the form of a sponge, if the proportion be considerable, but otherwise as a mud or slime which becomes detached from the anode surface and must be prevented from coming into contact with the cathode.
It consists of a stoneware tank with a thin sheet of platinum-iridium alloy at either end forming the primary electrodes, and between them a number of glass plates reaching nearly to the bottom, each having a platinum gauze sheet on either side; the two sheets belonging to each plate are in metallic connexion, but insulated from all the others, and form intermediary or bi-polar electrodes.
Knofler and Gebauer have also a system of bi-polar electrodes, mounted in a frame in appearance resembling a filter-press.
Through stuffing-boxes at the ends passed the two electrodes, made after the fashion of arc-light carbons, and capable of being approached together according to the requirements of the operation.
In 1895 the British Aluminium Company was founded to mine bauxite and manufacture alumina in Ireland, to prepare the necessary electrodes at Greenock, to reduce the aluminium by the aid of water-power at the Falls of Foyers, and to refine and work up the metal into marketable shapes at the old Milton factory of the Cowles Syndicate, remodelled to suit modern requirements.
A pair of electric arcs play between these electrodes and the molten steel, passing through the layer of slag, G, and generating much heat.
The lining of the crucible may be of either magnesite (MgO) or chromite (FeO Cr203) The whole furnace, electrodes and all, rotates about the line KL for the purpose of pouring out the molten FIG.
Electric furnaces are at an advantage over others as regards the removal of sulphur and of iron oxide from the molten steel, because their atmosphere is free from the sulphur always present in the flame of coal-fired furnaces, and almost free from oxygen, because this element is quickly absorbed by the carbon and silicon of the steel, and in the case of arc furnaces by the carbon of the electrodes themselves, and is replaced only very slowly by leakage, whereas through the Bessemer converter and the open-hearth furnace a torrent of air is always rushing.
Sodium hypochlorite can be prepared by the electrolysis of brine solution in the presence of carbon electrodes, having no diaphragm in the electrolytic cell, and mixing the anode and cathode products by agitating the liquid.
Furthermore his electrochemical investigations, and particularly his discovery of the important law of electrolysis, that the movement of a certain quantity of electricity through an electrolyte is always accompanied by the transfer of a certain definite quantity of matter from one electrode to another and the liberation at these electrodes of an equivalent weight of the ions, gave foundation for the idea of a definite atomic charge of electricity.
It has long been known that air and other gases at the pressure of the atmosphere were very perfect insulators, but that when they were rarefied and contained in glass tubes with platinum electrodes sealed through the glass, electricity could be passed through them under sufficient electromotive force and produced a luminous appearance known as the electric glow discharge.
Varley discovered the interesting fact that no current could be sent through the rarefied gas unless a certain minimum potential difference of the electrodes was excited.
The advantage of keeping the solution in motion is due partly to the renewal of solution thus effected in the neighbourhood of the electrodes, and partly to the neutralization of the tendency of liquids undergoing electrolysis to separate into layers, due to the different specific gravities of the solutions flowing from the opposing electrodes.
By introducing perforated shields of ebonite between the electrodes, so that the full current-density was only attained at the centres of the jets, these ill effects could be prevented.
The electrical pressure required to force a current of this intensity through the solution, and to overcome a certain opposing electromotive force arising from the more electro-negative impurities of the anode, depends upon the composition of the bath and of the anodes, the distance between the electrodes, and the temperature, but under the usual working conditions averages o-3 volt for every pair of electrodes in series.
Gangways are left between adjoining rows of tanks, and an overhead travelling-crane facilitates the removal of the electrodes.
The chief differences between the commercial systems of refining lie in the arrangement of the baths, in the disposition and manner of supporting the electrodes in each, in the method of circulating the solution, and in the current-density employed.
The various systems are often classed in two groups, known respectively as the Multiple and Series systems, depending upon the arrangement of the electrodes in each tank.
Under the series system only the first anode and the last cathode are connected to the conductors; between these are suspended, isolated from one another, a number of intermediate bi-polar electrode plates of raw copper, each of these plates acting on one side as a cathode, receiving a deposit of copper, and on the other as an anode, passing into solution; the voltage between the terminals of the tank will be as many times as great as that between a single pair of plates as there are spaces between electrodes in the tank.
With too% currentefficiency and a potential difference of 0.3 volt between the electrodes, t lb of copper should require about o-154 electrical horse-power hours as the amount of energy to be expended in the tank for its production.
Faraday observed that a large drop of mercury, resting on the flat bottom of a vessel containing dilute acid, changes its form in a remarkable way when connected with one of the electrodes of a battery, the other electrode being placed in the acid.
When this liquid is cold it is diluted with cold water, heated until all the soluble salts are dissolved, transferred to a tall, narrow beaker, and diluted to about 150 cc. The electrodes are attached to a frame connected with the battery and the beaker is placed on a stool, which can be raised so that the electrodes are immersed in the liquid and reach the bottom of the beaker.
The electrodes consist of two cylinders of platinum (placed one inside the other) about 75 mm.
Bredig's process consists in passing an electric arc between silver electrodes under water, when a brown solution is obtained.
A pressure of 1.5 volt usually suffices when the space between the electrodes is 2 in.
Silver peroxide, AgO, appears under certain conditions as minute octahedra when a solution of silver nitrate is electrolysed, or as an amorphous crust in the electrolysis of dilute sulphuric acid between silver electrodes.
A temperature of 70, and a reversal of the current (of low density) between two cast iron electrodes every few minutes, are the best working conditions.
These compounds are brought into solution by means of polysulphides of the alkali metals and the resultant liquor run into the cathode compartment of a bath, which is divided by diaphragms into a series of anode and cathode chambers; the anode divisions being closed and gas-tight, and containing carbon or platinum electrodes.
The electrical connections to the calorimeter are actually made to thin metallic members in the liquid argon (" electrodes " ).
It includes the receiver and a number of electrodes that directly stimulate the brainstem.
The graph above shows the effect of using offset electrodes on the power factor of the system.
During the stimulation session, self-adhesive electrodes must always be clipped on the special electrode cable of the Compex Mi Sensor system.
The stimulating electrodes cause the membrane potential to change a little.
The feed oxide is melted using graphite electrodes which then is allowed to solidify into a large block.
Components of ERP were recorded from 15 scalp electrodes.
Sodium in a sodium lamp a stream of electrons is passed between tungsten electrodes in a tube containing sodium vapor.
The electrodes need to be in contact with this solid electrolyte.
Arc furnace A steel melting furnace in which heat is generated by an arc between graphite electrodes and the metal.
The electrodes are inserted into the cochlea and replace the hair cells which are not working or are damaged.
They use nickel and cadmium as electrodes and aqueous potassium hydroxide as electrolyte.
They are given electric shocks, artificially induced diseases, have electrodes implanted in their brain.
We have used the transparent conductor indium tin oxide to fabricated electrode arrays with approximately 500 electrodes spaced at 60 Am.
Although it can be used with tuned induction loop antennas, it is usually operated with earthed electrodes separated by 25m to 100m.
Compton believes that the catalytic effects of nanotube electrodes are often misreported in the literature because the underlying science is not thoroughly investigated.
The stack is then sintered with the electrodes in-situ.
The coverage includes an introduction to electrodes and cells, to the electrochemical series and to the associated thermodynamics.
If, instead of using copper electrodes, we take plates of platinum, copper is still deposited on the cathode; but, instead of the anode dissolving, free sulphuric acid appears in the neighbouring solution, and oxygen gas is evolved at the surface of the platinum plate.
Thus, with a dilute solution of sulphuric acid and platinum electrodes, hydrogen gas is evolved at the cathode, while, as the result of a secondary action on the anode, sulphuric acid is there re-formed, and oxygen gas evolved.
Thus, if the current be passed through dilute sulphuric acid between hydrogen electrodes, and through a solution of copper sulphate, it will be found that the mass of hydrogen evolved in the first cell is to the mass of copper deposited in the second as i is to 31.8.
Many organic compounds can be prepared by taking advantage of secondary actions at the electrodes, such as reduction by the cathodic hydrogen, or oxidation at the anode (see Electrochemistry).
If we eliminate the reverse electromotive forces of polarization at the two electrodes, the conduction of electricity through electrolytes is found to conform to Ohm's law; that is, once the polarization is overcome, the current is proportional to the electromotive force applied to the bulk of the liquid.
Thus the statement that the migration constant or transport number for a decinormal solution of copper sulphate is o 632 implies that of every gramme of copper sulphate lost by a solution containing originally one-tenth of a gramme equivalent per litre when a current is passed through it between platinum electrodes, o 632 gramme is taken from the cathode vessel and o 368 gramme from the anode vessel.
Mallet, Comptes rendus, 1867, 64,' p. 226; 1868, 66, p. 349); by the electrolysis of solutions of sodium hydroxide, using nickel electrodes; by heating calcium plumbate (obtained from litharge and calcium carbonate) in a current of carbon dioxide (G.
Resistivity imaging uses an array of electrodes to measure apparent ground resistance.
The EEG was recorded from 12 subjects at 64 scalp electrodes.
The additional electrodes disturb the flow of gases around the spark plug tip and performance may even be reduced.
The risk for depth electrodes is approximately 1% per electrode; the incidence of meningitis is higher with subdural grids.
The monitoring is done through electrodes that are positioned in specific locations on the body.
Electrodes lead from the body to the monitoring devices give an understanding of what is happening during sleep.
Electrodes (small, sticky patches) covered with conducting jelly are placed on the patient's chest, arms, and legs.
In the nerve conduction study, small electrodes are placed on the skin over the muscles to be examined.
A stimulator delivers a very small electrical current (that does not cause damage to the body) through the electrodes, causing the nerves to fire.
The treatment consists of a series of electrical pulses that move into the brain through electrodes on the patient's head.
An EEG measures brain waves through small button electrodes that are placed on the child's scalp.
In the test, small electrodes are placed on or in the skin; the patterns of electrical activity are projected on a screen or over a loudspeaker.
The electrodes are connected to a computer that measures the heart's electrical impulses and records them in a zigzag patter on a moving strip of paper.
Electrodes are placed on the skin around the eye and the individual is subjected to a variety of stimuli so that the quality of eye movements can be assessed.
Electroencephalogram (EEG)-A record of the tiny electrical impulses produced by the brain's activity picked up by electrodes placed on the scalp.
Neurosurgical techniques in the brain such as implanting tiny electrodes directly into the cerebellum or cutting a portion of the hypothalamus have very specific uses and have had mixed results.
After the area is washed and dried, two metal electrodes are attached and fastened with straps.
Two gauze pads, one soaked in salt water or bicarbonate and the other in pilocarpine, a drug that stimulates sweating, are placed under the electrodes.
After about ten minutes, the electrodes are removed.
Electroencephalography-The recording of electrical impulses produced by the brain's activity via electrodes attached to a patient's scalp.
An automated auditory brainstem response (ABR) test, or brainstem auditory-evoked response (BAER) test, in which brainstem responses to sounds are monitored through small electrodes taped to the child's head.
Electrodes are surgically implanted into the cochlea through a hole drilled in the mastoid bone.
The electrodes in the cochlea collect the impulses from the stimulator and send them to the brain.
These electrical impulses flow through electrodes contained in a narrow, flexible tube that has been threaded into the cochlea during surgery and stimulate the auditory nerve.
This is because the implant's limited number of electrodes cannot hope to match the complexity of a human's 15,000 hair cells.
The surgeon then places the receiver-stimulator into a well made in the bone and gently threads the electrodes into the cochlea.
In this procedure, instead of applying the current across the skin, electrodes are implanted to stimulate peripheral nerves or nerves in the spinal cord.
An electroencephalogram (EEG), also called a brain wave test, is a diagnostic test which measures the electrical activity of the brain (brain waves) using highly sensitive recording equipment attached to the scalp by fine electrodes.
Electrodes are used to detect the electrical signals.
Although having electrodes pasted on the skin may feel strange, they only record activity and do not produce any sensation.
The technician either measures the scalp and marks the spots where small discs (electrodes) will be placed or fits the head with a special cap containing between 16 and 25 of these discs.
Neural prostheses contain many intricate components, such as implanted stimulators, electrodes, leads and connectors, sensors, and programming systems.
Biocompatibility between electrodes and body tissue is also required to prevent the patient from being harmed by contact with the device.
Surface electrodes attached to the scalp measure voltages in the brain.
NeuroSky, a 12-employee company in California founded in 1999, is using EEG waves (electroencephalography) to measure the brain's electrical activity through electrodes placed on the scalp.
First, a gel is put over a hundred electrodes on a person's scalp.
Neurofeedback allows patients to recognize brainwave activity by using electrodes that provide information instantly.
Electrodes are strategically placed on the patient's scalp so they can measure brainwaves.
Hughes, while engaged in experiments upon a Bell telephone in an electric circuit, discovered that a peculiar noise was produced whenever two hard electrodes, such as two wires, were - drawn across each other, or were made to touch each other with a variable degree of firmness.
Acting upon this discovery, he constructed an instrument which he called a " microphone," 6 and which consisted essentially of two hard carbon electrodes placed in contact, with a current passing through the point of contact and a telephone included in the same circuit.
One of the electrodes was attached to a sounding board capable of being vibrated by sound-waves and the other was held either by springs or weights in delicate contact with it.
The electrolysis is generally conducted with platinum electrodes, of which the cathode takes the form of a piece of foil bent into a cylindrical form, the necessary current being generated by one or more Daniell cells.