Caesium atomic clock, 1955.

Caesium atomic clock, 1955.
This was the first successfull atomic clock, with an accuracy of one second in 300 years. It measures time by counting the vibrations of caesium atoms. The caesium atoms are subjected to radio waves of a very high frequency as they pass down an evacuated tube. Each atom behaves as a small magnet and when the frequency of the radio waves correspond with the natural frequency of the atom it makes it reverse its polarity. These atoms are deflected into a detector by a magnet. By altering the frequency of the radio waves to maximise the number of atoms entering the detector it is possible to lock this frequency to that ot the caesium atoms. The frequency of the radio waves is derived from a quartz oscillator which is thus controlled by the vibration of the caesium atoms. The quartz oscillator can then be used to indicate time, as in the domestic quartz clock.
Currently on display in:
Making the Modern World
Year made :
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