The rate at which the magnetic field strength changes over time. It measures how quickly the field ramps up or down at any instant during a pulse. A changing magnetic field induces an electric field in nearby tissue, and a faster change produces a stronger induced field (Faraday's Law), so dB/dt is the primary driver of the induced-current mechanism behind PEMF, more so than the static peak strength. dB/dt varies throughout each pulse. Two commonly reported summaries are Peak dB/dt (the sharpest moment of one pulse, used for safety thresholds) and Slew Rate (the average rate across the rising edge, used as a performance metric).
dB/dt is how fast the magnetic field changes: the change in field strength divided by the time it takes, which is the steepness of the field-versus-time line. A steeper edge means a larger dB/dt. Because the body responds to a changing field rather than a steady one, dB/dt drives the stimulus; the single steepest point in a pulse is the Peak dB/dt.
