Editing Cathode (section)

{{Short description|Electrode where reduction takes place}}
{{Use dmy dates|date=January 2025}}
[[Image:Copper cathode 2.svg|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.

The electrode through which conventional current flows the other way, into the device, is termed an [[anode]].