How does a cesium clock work?

It is no surprise then that the international standard for the length of one second is based on atoms. Since 1967, the official definition of a second is 9,192,631,770 cycles of the radiation that gets an atom of the element called cesium to vibrate between two energy states. read more

Since 1967, the official definition of a second is 9,192,631,770 cycles of the radiation that gets an atom of the element called cesium to vibrate between two energy states. Inside a cesium atomic clock, cesium atoms are funneled down a tube where they pass through radio waves. read more

Cesium 133 is the element most commonly chosen for atomic clocks. To turn the cesium atomic resonance into an atomic clock, it is necessary to measure one of its transition or resonant frequencies accurately. This is normally done by locking a crystal oscillator to the principal microwave resonance of the cesium atom. read more

Most clocks work by having some regular event that can be counted. (Water clocks were an exception.) Until the 20th century, the norm was to use a pendulum and have it move clockwork. Electric clocks used a variety of other methods, including the frequency of the electricity supply. read more