Definition
An electronic component whose electrical resistance changes when light strikes it. In darkness it has high resistance and conducts very little current; as light intensity increases, its resistance drops and it conducts more current. Photoconductive cells are used in aircraft systems as light-sensing elements, such as in flame detectors for fire-warning systems and in automatic light-dimming circuits.
Plain English
A small part that lets electricity flow more easily when light hits it, and blocks electricity when it's dark. The brighter the light, the more current passes through it.
Context Anchor
Seen in aircraft electrical and warning-system discussions, especially where a system must detect light, flame, or changes in brightness.
Derivation
From Greek 'photo' meaning light, and 'conductive' from Latin 'conducere' meaning to lead through. Literally 'a cell that leads electricity through when light is present' — which is exactly what it does.
Why Pilots Care
Photoconductive cells are the sensing element in many engine fire-warning systems. When you see a fire warning light, a photoconductive cell may be what detected the flame and triggered the alert.
Analogy
It is like the light sensor in an automatic night light: when the light around it changes, the electrical behavior inside the device changes too.
Intuition Check
“Cell” does not mean a battery here. It means a small electrical sensing element used as part of a circuit.
Example Sentence 1
The engine fire-detection system uses a photoconductive cell that senses the bright light of a flame and triggers the warning in the cockpit.
Example Sentence 2
Replacement of the photoconductive cell restored proper operation of the light-sensing circuit in the instrument panel.