Piezoelectric Effect (Piezo Effect)
The piezoelectric effect is a phenomenon where certain materials generate an electric voltage when mechanical stress (pressure, force, or vibration) is applied to them.
This effect also works in reverse — when an electric field is applied, the material changes its shape slightly (mechanical deformation).
🧩 Types
-
Direct Piezoelectric Effect
- Mechanical stress → Electric charge.
- Used in sensors (like microphones, vibration sensors, pressure sensors).
-
Reverse Piezoelectric Effect
- Electric voltage → Mechanical deformation.
- Used in actuators (like speakers, ultrasound transducers, piezoelectric motors).
⚙️ Example Materials
- Quartz (SiO₂)
- Rochelle salt
- Barium titanate (BaTiO₃)
- Lead zirconate titanate (PZT)
🔋 Simple Example
When you press a quartz crystal, it creates a small electric voltage. When you apply a voltage to the same crystal, it vibrates.
🧠 Applications
- Microphones: Convert sound vibrations → electrical signals.
- Buzzers: Convert electrical signals → sound vibrations.
- Ultrasound machines: Generate and detect sound waves.
- Lighters: Spark generated by pressure on a piezo crystal.
- Sensors: Detect acceleration, force, or pressure.