The overall electrical strength delivered to the patient is determined by:

• A. Duration and intensity
• B. Carrier frequency and duty cycle
• C. Modulated frequency and pulse width
• D. On/off time and interpulse interval

Answer: (A)

Overall electrical strength depends on how strong the current is and how long it is applied. The tissue receives more stimulation when the current amplitude (intensity) is higher and when the current flows for a longer period (duration). This combination determines the total charge delivered to the tissue (and thus the exposure or dose you give the patient). Other parameters—like carrier frequency, duty cycle, pulse width, and on/off timing—shape the waveform and timing but don’t set the total exposure as directly as intensity and duration. So the best answer is that the overall strength is determined by duration and intensity.