May The Quartz Be With You

• Quartz timepieces operate on a principle called piezoelectricity. Piezoelectricity sounds so far-fetched you might expect to find it in a fantasy film or sci-fi movie. The concept is this, some crystals have electrical properties, if you compress them, they give off a charge. Conversely, if you send an electrical charge through them they contract or vibrate.
  
  

How They Give Off A Charge

• Molecules line up along the lattice of the crystal in asymmetrical configurations. When the crystal is compressed the molecules are forced into a formation which lines up the electrons. The line of electrons results in a flow of electricity.
  
  

Good Vibrations

• When a charge is applied to the crystal, it compresses. A steady charge results in a vibration or oscillation: the crystal expanding and contracting at tremendous speed. Scientist can calculate at what frequency a quartz crystal will vibrate, based on the voltage applied to it, and the thickness of the crystal.
  
  This is the basis of the clock. If you can calculate the speed of the crystal oscillation, you can in principle build a timer. Think of a pendulum clock. The clock-maker knows that each swing of the pendulum takes one second. The gears of the clock translate the pendulum's swings into the motions of the clock's hands. The crystal keeps time in a similar fashion, but instead of each swing representing a second, each oscillation of the crystal (vibrating at 32 kilohertz) takes a fraction of a second. Think of the crystal as a very fast and very small pendulum. The electronics of the watch amplify the oscillation and then translate these electrical pulses into the display format.