Svingfelt

Svingfelt is a term used in Norwegian and Danish to describe a field that varies in time in a periodic or quasi-periodic manner. It commonly refers to an oscillating field, such as an electric or magnetic field whose amplitude changes sinusoidally with time, and may include a phase relationship to a reference signal. The word is built from sving (oscillation) and felt (field). In English-language literature, the concept is usually described as an alternating field or oscillating field.

In mathematical terms, a time-harmonic svingfelt can be expressed as F(t) = Re{F0 e^{iωt}} for a complex amplitude F0 and angular frequency ω. For vector fields, the orientation may also change with time, yielding rotating fields in certain applications. Examples include electric svingfelt in alternating-current circuits and magnetic svingfelt in radio-frequency or resonance experiments.

Applications of svingfelt appear across several disciplines. In electrical engineering, it underpins the operation of transformers, inductors, and RF antennas driven by sinusoidal signals. In physics and medical imaging, oscillating magnetic or electric fields drive spin transitions in techniques such as nuclear magnetic resonance and magnetic resonance imaging. In optics, time-varying fields describe modulated light and related coherent-control processes.

Notes: The term is comparatively common in Scandinavian contexts; English-language texts typically use alternating field or oscillating field. See also alternating current, phasor, resonance.