Definition
The release of electrons from certain materials when light strikes them. Photoelectric devices convert light energy directly into electrical signals or current, and are used in sensors that detect light, measure its intensity, or trigger an electrical response when light is present or interrupted.
Plain English
When light hits certain materials, it knocks tiny electric particles loose and produces electricity. This effect is used in sensors that 'see' light and react to it.
Context Anchor
Seen in discussions of photoelectric cells, light sensors, some detection systems, and electrical devices that respond to light.
Derivation
From the Greek 'photo-' meaning light, and 'electricity.' Literally 'electricity from light' — which is exactly what the effect produces.
Why Pilots Care
Several aircraft systems rely on photoelectric sensors — smoke detectors in cargo bays and lavatories, some fire-warning systems, and certain fuel and ice-detection sensors. Knowing the principle helps when troubleshooting why a sensor might give a false warning (dirt, contamination, or a failed light source can all interrupt the effect).
Analogy
A small solar garden light is a familiar example: sunlight hits the panel during the day and creates an electrical effect that charges the battery.
Grounding Statement
Picture light hitting a special surface and making a tiny electrical signal that a device can use.
Intuition Check
Photoelectricity does not mean electricity used to make light. It means light producing an electrical effect.
Example Sentence 1
The cargo compartment smoke detector uses photoelectricity — smoke particles scatter light onto a sensor, which triggers the warning.
Example Sentence 2
Photoelectric cells convert sunlight into electrical signals for certain cockpit instrument displays.