Which waveform delivers current in bursts with off-times?

• A. Direct current (DC) provides a constant unidirectional flow.
• B. Alternating current (AC) reverses direction sinusoidally.
• C. Pulsed current delivers current in bursts with off-times.
• D. Mixed current combines DC and AC.

Answer: (C)

Current delivered in bursts with off-times is pulsed current. A pulsed waveform sends brief bursts of current and then has intervals where no current flows. This pattern is defined by how long each pulse lasts, how strong it is, and how frequently the pulses repeat. Those off-times let tissues and the electrical circuit reset, helping control the average current and reduce heating or fatigue.

Direct current is a constant flow in one direction with no off periods, so it doesn’t come in bursts. Alternating current continuously reverses direction in a sinusoidal manner, also without defined off intervals. Mixed current combines DC and AC components but isn’t inherently characterized by bursts with gaps.