Stimulus amplitude refers to:

• A. The frequency of the stimulation
• B. The duty cycle of the output
• C. The strength or intensity, in volts or milliamps
• D. The duration of each pulse

Answer: (C)

Stimulus amplitude is the strength or intensity of the electrical stimulus, describing how much energy is delivered to the tissue. In practice, it’s the voltage or the current (measured in milliamps) that determines how strongly nerve fibers are activated. This parameter controls the size of the response: increase amplitude to recruit more fibers and produce a stronger sensation or muscle contraction, but be mindful of comfort and safety to avoid discomfort or tissue damage. The other terms describe different aspects of the stimulus: frequency is how often pulses occur per second, the duty cycle is the proportion of time the stimulus is on during a cycle, and the duration of each pulse (pulse width) is how long a single pulse lasts.