Which of the following is NOT a listed number of phases?

• A. Monophasic
• B. Biphasic
• C. Polyphasic
• D. Triphasic

Answer: (D)

Understanding how current is described by the number of phases helps you predict charge delivery and tissue response. Monophasic means the current flows in one direction during each pulse. Biphasic means the current reverses direction within the pulse, balancing charge. Polyphasic means there are more than two phases in the cycle, offering additional waveform shapes for comfort and effectiveness. Triphasic would imply three phases, but standard practice materials typically list monophasic, biphasic, and polyphasic as the common categories for number of phases. Therefore, triphasic isn’t a commonly listed category, making it the correct choice for what isn’t a listed number of phases.