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terminal through which electric current passes between metallic and nonmetallic parts of an electric circuit. In most familiar circuits current is carried by metallic conductors, but in some circuits the current passes for some distance through a nonmetallic conductor.
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 through which current leaves an electric device. In electrolysiselectrolysis
, passage of an electric current through a conducting solution or molten salt that is decomposed in the process. The Electrolytic Process

The electrolytic process requires that an electrolyte, an ionized solution or molten metallic salt, complete an
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, it is the negative electrode in the electrolytic cell.



(1) In an electron tube or a gas-discharge tube, the electrode that is the source of electrons that ensure the conductivity of interelectrode space in a vacuum or maintain the steadiness of the passage of an electric current through the gas. Depending on the mechanism of emission of electrons, there exist thermionic cathodes, photocathodes, and cold cathodes.

(2) The negatively charged electrode (pole) of a source of current (galvanic cell, storage battery).

(3) The electrode of an electrolytic cell, an electric arc, and other similar devices that are connected to the negative pole of a source of current.


The terminal at which current leaves a primary cell or storage battery; it is negative with respect to the device, and positive with respect to the external circuit.
The primary source of electrons in an electron tube; in directly heated tubes the filament is the cathode, and in indirectly heated tubes a coated metal cathode surrounds a heater. Designated K. Also known as negative electrode.
The terminal of a semiconductor diode that is negative with respect to the other terminal when the diode is biased in the forward direction.
(physical chemistry)
The electrode at which reduction takes place in an electrochemical cell, that is, a cell through which electrons are being forced.


1. the negative electrode in an electrolytic cell; the electrode by which electrons enter a device from an external circuit
2. the negatively charged electron source in an electronic valve
3. the positive terminal of a primary cell


The terminal on a device that emits current. In the cathode ray tubes (CRT) of the bulky TVs and monitors prior to flat panels, the negative cathode emits electrons that are attracted to the positive "anode." Current flows out of cathodes and into anodes. Depending on the application, a cathode may be considered positive or negative. Derived from Greek, cathode and anode mean "down" and "up" respectively. See electrode and cold cathode.

Cathode Emitters
In vacuum tubes, the cathodes are the emitters, and the anodes are the collectors.
References in periodicals archive ?
In addition, the data also indicates that some adhesives, while very tolerant of many severe environments, are not a proper choice when used to adhere cathodically protected rubber to metal articles, as early failure can be induced in the laboratory.
This defect occurred on a cathodically protected natural gas pipeline south of Oswego, NY and was ultimately attributed to induced AC corrosion (1).
Table 9 show that, overall, the cathodically electrodeposited films of all adducts exhibited excellent corrosion resistance properties, as the corrosion creep-age across the scribe was very low, between 1.
Adhesives for bonding cathodically protected rubber to metal devices," is based on a paper presented at the Fall 1990 Rubber Division meeting "Adhesion and wetting: Similarities and differences," is based on a paper presented at the Fall 1990 Rubber Division meeting "Low temperature sealing capabilities of fluoroelastomers," is based on a paper presented at the 1991 SAE exposition and is reprinted with permission 1991, SAE, Inc.
Common types of corrosion-resistant tanks and lines include fiberglass, fiberglass-coated steel, cathodically protected steel, or some combination thereof.
The majority of underground pipelines are externally coated and cathodically protected to mitigate corrosion.
polyvinyl chloride (PVC), and Schedule 40 Grade B Steel (coated, wrapped and cathodically protected)
PTh is anodically coloring and PEDOT is cathodically coloring polymers.
In 1975, ULC (Underwriters Laboratories of Canada) issued the first listing for cathodically protected steel tanks with a rigid polyurethane coating.
To allow the free flow of electric charge used to cathodically protect the pipe's metal, Fomo's system also includes newly developed low-density foam that allows the passage of electrical charges, and is applied around the pipe.
Since 1990, natural gas utilities have installed modern plastic pipes used for delivering gas at low pressure at a rate of 30,000 miles per year, and cathodically protected steel mains used for high-pressure delivery at a rate of 1,500 miles per year, both connecting new customers and upgrading existing pipeline infrastructure.
312), (314) This mechanism of adhesion loss has been reported for epoxy and heat-cured acrylic and polybutadiene coatings on cathodically protected steel.