cathode

thumb|Diagram of a copper cathode in a [[galvanic cell (e.g. a battery). Positively charged cations move towards the cathode allowing a positive current i to flow out of the cathode.]]

AI overview

A cathode is the positive terminal in a battery or similar device where positively charged particles are attracted and where electric current flows out. It matters because it's one of the two essential parts of a battery that makes electrical current flow, which powers everything from flashlights to electronics.

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Commons category: Cathodes

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~17 min read

Article

14 sections

Contents

Charge flow
Etymology
In chemistry
Electrolytic cell
Galvanic cell
Electroplating metal cathode (electrolysis)
In electronics
Vacuum tubes
Hot cathode
Cold cathode
Diodes
See also
References
External links

thumb|Diagram of a copper cathode in a [[galvanic cell (e.g. a battery). Positively charged cations move towards the cathode allowing a positive current i to flow out of the cathode.]]

A cathode is the electrode from which a conventional current leaves a polarized electrical device such as a lead–acid battery. This definition can be recalled by using the mnemonic CCD for Cathode Current Departs. Conventional current describes the direction in which positive charges move. Electrons, which are the carriers of current in most electrical systems, have a negative electrical charge, so the movement of electrons is opposite to that of the conventional current flow: this means that electrons flow into the device's cathode from the external circuit. For example, the end of a household battery marked with a + (plus) is the cathode.