Barber State Board Exam Complete Practice Test

The device used to apply current to a client's skin in electrotherapy is an electrode. Electrodes serve as the interface between the electrotherapy machine and the client's skin, allowing electrical currents to be delivered in a controlled manner for therapeutic benefits. They can come in various forms depending on the type of treatment, including adhesive pads, metal plates, or specialized tools that target specific areas of the skin.

Understanding the role of an electrode is crucial as it directly influences the effectiveness of the electrotherapy treatment. By ensuring proper placement and conductivity, electrodes can enhance treatment efficacy whether it's for muscle stimulation, pain relief, or skin rejuvenation.

Other options listed, like a transformer and generator, are involved in the production and modification of electrical energy but do not directly interact with the client's skin. Conductors are materials that can carry electricity but are not specifically designed for application in electrotherapy treatments.