Definition
Electricity produced directly from heat. When two dissimilar metals are joined to form a junction and that junction is heated, a small voltage appears across the open ends of the wires. The amount of voltage depends on the metals used and the temperature difference between the heated junction and the cooler reference end.
Plain English
Electricity made from heat. Join two different metals together, heat the spot where they meet, and a small voltage appears in the wires. The hotter the junction, the more voltage you get.
Context Anchor
Seen in discussions of aircraft temperature instruments, especially engine temperature probes and their wiring.
Derivation
From Greek 'thermos' meaning heat, plus 'electricity.' Literally 'heat-electricity' -- electricity produced by heat rather than by a battery or generator.
Why Pilots Care
Several common engine instruments rely on this principle. The CHT and EGT gauges produce no electricity of their own when the engine is cold; the reading you see in flight is generated entirely by the heat at the probe. This is why these gauges need no external power source -- the heat itself is the power source.
Grounding Statement
Picture a temperature probe sitting in a hot exhaust stream: the heat difference at the probe creates a tiny electrical signal that the instrument turns into a temperature reading.
Intuition Check
Thermoelectricity does not mean any electrical system that gets hot. It means electricity produced by a temperature difference.
Example Sentence 1
The CHT gauge works on the principle of thermoelectricity -- heat at the cylinder head produces the small voltage that moves the needle.
Example Sentence 2
Mechanics test the thermoelectric circuit to confirm accurate temperature readings before flight.