Cathode

Part of speech: noun

Pronunciation: /ˈkæθ.oʊd/

Definitions

1. An electrode involved in reduction within an electrochemical system functions by emitting electrons in vacuum tubes while also serving as the entry point for electric current in diodes
2. This electrode facilitates reduction reactions in electrochemical cells, discharges electrons in vacuum tubes, and acts as the current entry terminal in diodes
3. An electrode that plays a crucial role in electrochemical processes by allowing electrons to flow into an external circuit, while also serving as the primary terminal for current intake in devices like diodes and emitting electrons in vacuum environments

Etymology: Michael Faraday needed a name for the electrode where electrons leave an electrolytic cell, and in 1834 he got one from the Cambridge polymath William Whewell, who coined it from Greek. The pieces are "kata-", meaning "down", and "hodos", meaning "way" or "journey", which together gave "kathodos", a "way down" or descent. Faraday's own reasoning was that current was a flow moving down through the cell, so the electrode where it exited deserved a name built on that idea. The word has a neat counterpart. Faraday had already paired it with "anode", formed on "ana-" ("up"), so the two terms describe a current's path as a descent and an ascent. Scientists later kept the pairing even as the physics behind it was refined. Electrons actually move in the opposite direction to conventional current, so the cathode is where electrons enter the cell from the external circuit in electrolysis, while in a battery it is the electrode that releases them outward. The name stuck regardless, because the terms were defined by the direction of the current rather than the electrons.

Synonyms: negative electrode