Who is credited with discovering high frequency current?

• A. Direct current
• B. Alternating current
• C. Static electricity
• D. High frequency current

Answer: (D)

High frequency current is the type of electricity used in many beauty devices, and its historical development is tied to Nikola Tesla, whose work on high‑frequency oscillators and the Tesla coil made rapid alternating currents practical. In cosmetology, this current is used with glass electrodes to create therapeutic effects like mild heating, antiseptic action, and stimulation of the skin.

Among the listed options, the one that best fits answering a question about the discovery is the term that describes high‑frequency current itself, since the others refer to different forms of electricity (direct current, alternating current, static electricity) and don’t address who discovered this specific type. However, the widely accepted attribution for discovering high‑frequency current is Nikola Tesla.