The working of the quartz crystal in the watch is based on the—

Q. The working of the quartz crystal in the watch is based on the—

1. Photoelectric Effect
2. Johnson Effect
3. Piezoelectric Effect
4. Edison Effect

Answer: Piezo-electric Effect.

Piezoelectric Effect

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Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress.
An important feature to note about this phenomenon is that the process is reversible. The inverse piezoelectric effect refers to a deformation of these materials that results from the application of an electric field. The deformation could lead to either tensile or compressive strains and stresses in the material depending upon the direction of the electric field

Examples of Piezoelectric materials

Some examples of piezoelectric materials are PZT (also known as lead zirconate titanate), barium titanate, and lithium niobate. These man-made materials have a more pronounced effect (better material to use) than quartz and other natural piezoelectric materials.Quartz is a tectosilicate mineral that is the second most common mineral in Earth's continental crust. Its crystal structure is a framework of SiO₄ silicon-oxygen tetrahedra. Each shares an oxygen atom with another tetrahedron, so the overall chemical formula is SiO₂ or silica.

The piezoelectric effect was discovered in 1880 by two French physicists, brothers Pierre and Paul-Jacques Curie, in crystals of quartz, tourmaline, and Rochelle salt (potassium sodium tartrate). They took the name from the Greek work piezein, which means "to press."