Final answer:
High-frequency machines only require one electrode.
Step-by-step explanation:
High-frequency machines, also referred to as Tesla or violet rays, operate with a single electrode. Functioning on high-frequency alternating current, they generate a high-voltage, low-current electric current. This current is directed through a glass electrode containing neon or argon gas, resulting in the emission of a distinctive violet or purple light. The glass electrode, often held by the user, serves as the conduit for applying the electric current to the skin. Commonly used in skincare and aesthetic treatments, these machines aim to promote circulation, enhance skin tone, and address various skin concerns through the application of controlled high-frequency electrical currents to the skin's surface.