Definition
An early type of wet primary electrochemical cell that produces electricity through a chemical reaction between a copper electrode immersed in a copper sulfate solution and a zinc electrode immersed in a dilute sulfuric acid or zinc sulfate solution, with the two solutions separated by a porous barrier. It produces a steady output of about 1.1 volts and was historically used as a reference standard for voltage.
Plain English
An old-style battery cell made from copper and zinc sitting in two different liquids. The chemical reaction between the metals and liquids produces a steady, reliable electrical voltage.
Context Anchor
Seen in basic aircraft electrical and battery theory, especially when learning how chemical action can produce voltage.
Derivation
Named after John Frederic Daniell, the British chemist who invented it in 1836. Knowing it is an inventor's name (not a technical descriptor) helps avoid trying to decode the meaning from the word itself.
Why Pilots Care
Pilots will not encounter Daniell cells in modern aircraft, but the term appears in foundational electrical theory used to explain how batteries produce voltage. Understanding the principle behind it helps make sense of how today's aircraft batteries work.
Analogy
A Daniell cell is like one small building block of a battery. By itself it makes only a small voltage; connect cells together and you can get more useful electrical power.
Intuition Check
Do not read “cell” here as a living cell. In electrical use, a cell is one single chemical unit that produces voltage.
Example Sentence 1
The textbook used the Daniell cell as a simple example to explain how a chemical reaction between two different metals can produce a steady voltage.
Example Sentence 2
The Daniell cell provided reliable voltage in laboratory setups before modern aircraft batteries were developed.