Passive Care Exam 1 Electrical Stimulation Practice Test

The relationship between how strong the electrical current is and how long the pulse lasts is described by the strength–duration curve. This curve shows that short pulses require higher current to reach the excitation threshold, while longer pulses can achieve excitation with a lower current. It reflects how nerves have a threshold that depends on pulse duration, not a fixed current value. Key terms here are rheobase (the smallest current needed if the pulse is very long) and chronaxie (the pulse duration at twice the rheobase). So, as you adjust duration, you shift the required amplitude to reach threshold, revealing why longer, gentler pulses can sometimes be just as effective as brief, strong ones. This concept is distinct from Ohm’s law, time-constant ideas, or frequency-response notions.