frekvens

Frekvens is the number of occurrences of a repeating event per unit of time. In physics and engineering, frequency f is usually measured in hertz (Hz). One hertz equals one cycle per second; higher frequencies use kilohertz (kHz), megahertz (MHz), or gigahertz (GHz). The frequency of a periodic signal is the inverse of its period T: f = 1/T. The angular frequency ω = 2πf is the rate of rotation of the phase, measured in radians per second.

Frekvens appears in many domains: electromagnetic waves (radio, light), sound waves, and other mechanical vibrations. In audio, human hearing roughly spans 20 Hz to 20 kHz. In electrical power distribution, mains electricity operates at 50 Hz or 60 Hz depending on region. In radio and communications, carrier frequencies range from kilohertz to gigahertz, with information encoded by modulation.

Measurement and instruments are used to determine frequency. Frequency counters, oscilloscopes with time-base measurements, and spectrum analyzers are common tools. In practice, f can be found by counting cycles in a time window or by measuring the period T. Stability and drift of frequency are important in clocks, communications, and navigation.

In signal processing, frequency analysis uses Fourier transforms to convert time-domain signals into frequency-domain spectra, revealing harmonic content and bandwidth.

Etymology: the term frekvens is related to the word frequency, from Latin frequentia; the unit hertz honors Heinrich Hertz.