A biphasic electrical current is defined as:

A biphasic electrical current is defined as:

• A. A pulse with two phases; current flows in both directions.
• B. A pulse that travels in a single direction only.
• C. A continuous direct current.
• D. Random bursts with no defined phase.

Answer: (A)

Biphasic current is defined by a single pulse that contains two phases, with the current reversing direction within that pulse. This means one phase carries current in one direction and the second phase carries current in the opposite direction, so over the duration of the pulse there is no net flow in one direction. This balancing of charge helps prevent buildup at the electrode-tissue interface, reducing tissue polarization and potential irritation or damage during repeated stimulation. In practice, the two phases may be equal or nearly equal in magnitude (balanced or symmetrical) to ensure minimal net DC over time, though some applications use slight asymmetry while still aiming for zero average charge. This differs from a pulse that only moves in a single direction (monophasic), from continuous direct current which is unidirectional and steady rather than alternating within each pulse, and from irregular bursts that lack a defined two-phase structure.

Biphasic current is defined by a single pulse that contains two phases, with the current reversing direction within that pulse. This means one phase carries current in one direction and the second phase carries current in the opposite direction, so over the duration of the pulse there is no net flow in one direction. This balancing of charge helps prevent buildup at the electrode-tissue interface, reducing tissue polarization and potential irritation or damage during repeated stimulation.

In practice, the two phases may be equal or nearly equal in magnitude (balanced or symmetrical) to ensure minimal net DC over time, though some applications use slight asymmetry while still aiming for zero average charge.

This differs from a pulse that only moves in a single direction (monophasic), from continuous direct current which is unidirectional and steady rather than alternating within each pulse, and from irregular bursts that lack a defined two-phase structure.