Q. The working of the quartz crystal in the watch is based on which of the following effects? (UPSC Prelims 1993)
Answer: Piezo-electric Effect
Notes: Inside a quartz clock or watch, the battery sends electricity to the quartz crystal through an electronic circuit. The quartz crystal oscillates (vibrates back and forth) at a precise frequency: exactly 32768 times each second. This is due to Piezoelectric Effect. Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. When reversed, an outer electrical field either stretches or compresses the piezoelectric material.