What is the type of current referred to as high frequency?

High-frequency current refers to alternating current (AC) that oscillates at a frequency beyond the standard power line frequency of 50 or 60 Hz. In various applications, particularly in electrical and electronic systems, this type of current is utilized for specific purposes, such as in radio frequency transmissions, medical therapies, and some types of signal processing.

Alternating current can vary in frequency, and high-frequency AC usually falls within the range of kilohertz (kHz) to megahertz (MHz). It is particularly important in therapeutic modalities such as diathermy and certain skin treatments in esthetics, where it is used to produce thermal effects or stimulate metabolic activity.

Direct current, while also crucial in many applications, provides a steady, constant flow of electricity and does not oscillate, therefore it is not classified as high frequency. Pulsed current likewise refers to a flow of electric charge that is interrupted or periodic, but it does not maintain the high-frequency oscillations of alternating current. Static current is essentially a stationary electrical charge and does not involve any current flow, making it irrelevant in the context of high-frequency discussions.