Use a multimeter to measure the forward resistance of a diode

The resistance value measured is its DC resistance. Since the diode is a nonlinear element, its voltage and current are not proportional, so the current passing through the tube is different, and the measured DC resistance is also different. When measuring with the ω×1 gear, since the internal resistance of the multimeter is small, the current passing through the diode is large, and the tube works at point q1, the DC resistance (vd1/id1) is small. When measuring with the ω×100 gear, the internal resistance of the multimeter is large, the current passing through the diode is small, and the tube works at point q2, so the DC resistance (vd2/id2) is large.