Definition

1. Noun:
   • The positively charged terminal of a voltaic cell or storage battery that supplies current: In a primary cell (like a battery), the cathode is the terminal where conventional current leaves the cell. It is the positive terminal during discharge.
   • A negatively charged electrode that is the source of electrons entering an electrical device: In devices that consume electrical power, such as vacuum tubes, cathode ray tubes, or electrolytic cells, the cathode is the electrode from which electrons flow out into the device.

Usage and Examples

• In a battery (discharging):

  • Connect the wire to the cathode, which is the positive terminal of this battery.
  • During discharge, the cathode is reduced as it gains electrons.

• In an electrical/electronic device:

  • In a cathode ray tube, electrons are emitted from the heated cathode.
  • The cathode of this diode is marked with a band.

Advanced Usage and Notes

• Electrochemical Context: The definition of cathode (positive or negative) depends on whether the device is generating power (like a battery) or using power (like an electrolytic cell). It is defined by the direction of current or the chemical reaction (reduction occurs at the cathode).
• Cathode Material: Often made of specific materials to facilitate electron emission or reduction reactions.

Variants and Related Words

• Cathodic (adj): Pertaining to or involving a cathode.
  • The cathodic reaction is crucial for corrosion protection.
• Cathodically (adv): In a cathodic manner.
• Cathode Ray (n): A stream of electrons emitted from the cathode in a vacuum tube.
  • Cathode rays were used in old television sets.

Synonyms

• Negative electrode (in an electron-consuming device).
• Positive terminal (in a power-supplying cell during discharge).

Antonyms

• Anode: The electrode where conventional current enters a device or the negative terminal of a discharging battery.

Related Phrases and Compounds

• Cathode ray tube (CRT): A vacuum tube where images are produced by a beam of electrons from a cathode.
• Cold cathode: A cathode that emits electrons without being heated.
• Hot cathode: A cathode heated to emit electrons thermionically.

Noun

1. the positively charged terminal of a voltaic cell or storage battery that supplies current
2. a negatively charged electrode that is the source of electrons entering an electrical device