Definition
An electrical voltage produced by certain crystals when they are mechanically stressed (squeezed, bent, or struck). The same crystals also work in reverse: when a voltage is applied across them, they deform slightly. Common piezoelectric materials include quartz and certain ceramics.
Plain English
Some crystals create a small electric charge when you press on them, and they flex a little when you put electricity through them. It's a two-way relationship between physical pressure and electricity.
Context Anchor
Seen in aircraft system descriptions for sensors that turn pressure, sound, or vibration into an electrical signal.
Derivation
From the Greek piezein, meaning 'to press' or 'to squeeze,' combined with 'electricity.' Literally 'pressure-electricity.' The name describes exactly what happens — pressure on the crystal produces an electrical output.
Why Pilots Care
Many of the small sensors aboard modern aircraft rely on piezoelectric crystals to convert physical events — vibration, pressure, acceleration — into electrical signals the avionics can read. Understanding the principle helps make sense of how these sensors work and why they can fail if the crystal element is cracked or contaminated.
Grounding Statement
Squeeze the crystal, get a voltage. Apply a voltage, the crystal squeezes itself.
Intuition Check
Piezoelectricity is not ordinary stored electricity like a battery. The electrical signal is created when a special material is pressed, bent, or vibrated.
Example Sentence 1
The engine knock sensor uses piezoelectricity to detect detonation, generating a small voltage when vibration from the cylinder reaches the crystal.
Example Sentence 2
Technicians replaced the piezoelectric crystal in the fuel pressure transmitter during the inspection.