Constant (atomic clock)

An atomic clock measures time by monitoring the resonant frequency of atoms. Its working relies on the fact that atoms have different energy levels.

The unit second (s) is defined by the duration of 9.192.631.770 cycles of the radiation emitted by the ¹³³Cs atomic clock.

Related concepts

• base units
• constant (Avogadro)
• constant (Boltzmann)
• constant (electron charge)
• constant (Planck)
• constant (speed of light)
• second
• time