In the generation of a potential difference, what type of action can be applied to crystals?

The generation of a potential difference in crystals is closely related to the piezoelectric effect, which occurs when certain materials, such as quartz and specific ceramics, generate an electric charge in response to mechanical stress. Twisting the crystals can alter the alignment of their internal structures, thus generating a potential difference. This phenomenon arises because the twisting action changes the spatial arrangement of the atoms within the crystal lattice, leading to a displacement of charges and the establishment of an electrical potential.

Other actions, while they may affect the physical structure of a crystal, do not specifically induce the same electrical response as twisting. For instance, bending can change the lattice structure but does not necessarily generate the same focused effect, and compressional forces may lead to changes as well, but twisting is particularly effective in aligning the electrical dipoles in the material. Thus, twisting is the most direct and effective action for generating a potential difference in crystals.