What does it mean when we say quartz crystal vibrates.it is very strange to read that a particular solid vibrates with period of 10^(-6) seconds.does it mean something else when it is written quartz crystal vibrates.One thing which is in back of my mind is that they may be talking about electrons moving from one energy level to another and coming back.please help to eradicate the doubt
Quartz crystal is a piezoelectric material. It produces and accumulates electric charge when subjected to mechanical stress. The piezoelectric effect works both ways. Not only is electric charge produced when mechanical stress is applied, but also mechanical stress appears when electric charge is applied.
Mechanical stress, if applied in sufficient amount, is accompanied by mechanical strain, or deformation of the material under stress. In quartz crystal, strain appears as a bending of the crystalline structure when electric charge is applied across the plane of a crystalline sheet.
An oscillator circuit composed of an amplifier and a resonator applies charge to the thin sheet of quartz crystal, and the crystal mechanically vibrates because of the reversible piezoelectric effect. The crystal acts as the resonator in the circuit. It vibrates at a desired frequency based on its thickness, shape, and the lattice plane from which the crystal is cut. The vibrating crystal acts as a filter which eliminates all electric signals with the exception of the desired frequency.
The vibrating quartz crystal feeds back its frequency to the amplifier. As long as electric charge is continuously applied, and temperature does not vary too much, the mechanical vibrations of the crystal resonator are regular and dependable.