What does piezoelectricity refer to?

Piezoelectricity refers to the electrical voltage that is generated when certain materials, typically certain types of crystals, are subjected to mechanical stress, such as squeezing or deformation. When these materials are compressed, they generate a charge due to the displacement of charged particles within the crystal lattice. This property is utilized in various applications, including sensors, actuators, and energy harvesting devices.

The other options, while related to different forms of energy conversion, do not accurately describe the piezoelectric effect. For example, electricity produced from heat describes thermoelectricity, while electricity created by light refers to photovoltaic effects, and electricity generated from motion relates to electromagnetic induction. These concepts differ fundamentally from piezoelectricity, which is specifically associated with the mechanical deformation of certain materials.