sekundes

Sekundes is a unit of time in the International System of Units (SI). It is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. This definition was adopted in 1967 and has been the international standard since then.

The symbol for the second is "s". It is one of the seven base units of the SI, alongside the meter, kilogram, ampere, kelvin, mole, and candela. Historically, the second was defined based on the Earth's rotation, but this proved to be not constant enough for precise scientific measurement. The caesium atomic clock provides a highly stable and reproducible standard.

The second is a fundamental unit used in many scientific and engineering disciplines. It is used to measure durations of events, speeds, frequencies, and countless other physical quantities. It is also the basis for other time-related units, such as minutes (60 seconds) and hours (3600 seconds). The fractional parts of a second are often expressed using SI prefixes, such as milliseconds (thousandths of a second) or microseconds (millionths of a second).