periodetiden

Periodetiden is a term used to describe the duration of one cycle of a periodic phenomenon—the time interval between two successive identical points in the cycle. It is the temporal length of one period and is the reciprocal of the frequency of the process: f = 1/T, or T = 1/f. The SI unit for period is the second, but period lengths can range from milliseconds in electronics to years in astronomical or geological contexts.

Periodetiden is used across disciplines to characterize repeating processes such as a pendulum's swing, alternating current, circadian rhythms, or seasonal cycles. In data analysis, periodetiden can be estimated from peaks in a time series or via spectral methods like Fourier analysis, which identify dominant frequencies and convert them to periods.

Examples: a simple pendulum of about 1 meter has a period near 2 s; a 50 Hz AC signal has a period of 0.02 s; Earth's orbital period around the Sun is about 365.25 days; the human circadian cycle is close to 24 hours.

Notes: In some contexts, Swedish texts may prefer terms like ‘periodens längd’ or ‘periodtid’; the exact terminology can vary by field. Periodetiden is distinct from the concept of a geological period, which denotes a broader interval in the geologic time scale rather than the duration of a process.