What are the current types?

• A. Direct current vs Alternated
• B. Direct vs Alternating
• C. Single phase vs Multi-phase
• D. Pulsed current vs continuous current

Answer: (B)

The main distinction here is how the current behaves over time: whether it keeps the same direction (unidirectional) or reverses direction periodically. This is captured by calling one type direct current and the other alternating current. Direct current flows in one direction with a constant polarity, which leads to steady ion movement and potential polarization effects at the electrodes. Alternating current reverses polarity, so there’s no net charge buildup over time, which changes how tissues respond and is often used for different stimulation effects.

The other phrasing describes how the current is delivered (pulsed vs continuous) or how many phases the waveform has, which are important considerations but not the fundamental way we classify current types. Therefore, direct versus alternating is the standard, best way to denote the primary current types.