Which type of electricity is generated when crystals are squeezed?

The generation of electricity when crystals are squeezed is referred to as piezoelectricity. This phenomenon occurs in certain materials, particularly crystals, where mechanical stress induces an electrical charge. When these materials are compressed or deformed, their internal structure leads to an imbalance of electrical charges, creating a voltage across the material. This property is widely utilized in various applications, such as pressure sensors, microphones, and actuators, where it is essential to convert mechanical energy into electrical energy.

The other types of electricity listed involve different processes: thermo-electricity relates to the generation of electrical energy from temperature differences, photo electricity involves electricity generated from light (generally through photovoltaic effects), and magnetic electricity deals with the generation of electric currents through magnetic fields. Each of these concepts focuses on specific principles and applications, making piezoelectricity unique in its direct correlation to mechanical pressure and deformation in crystals.