|an extremely accurate clock in which an electrical oscillator is controlled by the natural vibrations of an atomic or molecular system such as caesium or ammonia|
|an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle.|
|the offspring of a zebra and a donkey.|
An extremely precise clock whose rate is controlled by a periodic process (such as vibration, or the absorption or emission of electromagnetic radiation) that occurs at a steady rate in atoms or molecules. The standard atomic clock is based on the vibrations of cesium atoms and is so accurate that it would gain or lose less than one second in three million years. Atomic clocks are used to help track satellites, run navigation systems, and study movements of the Earth's crust.
type of clock that uses certain resonance frequencies of atoms (usually cesium or rubidium) to keep time with extreme accuracy. The electronic components of atomic clocks are regulated by the frequency of the microwave electromagnetic radiation. Only when this radiation is maintained at a highly specific frequency will it induce the quantum transition (energy change) of the cesium or rubidium atoms. In an atomic clock these quantum transitions are observed and maintained in a feedback loop that trims the frequency of the electromagnetic radiation; like the recurrent events in other types of clocks, these waves are then counted.
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