1.实验原理和方法例1用伏安法测额定电压为2.5伏的小灯泡正常发光时的电阻.(1)在未完成的电路中(图1),导线的接头M应连在滑动变阻器的__接线柱上.(2)闭合电键K后,伏特表的示数为0.5伏,要使小灯泡正常发光,滑片P应向__移动.(3)小灯泡正常发光时,安培表示数如图2所示,是__ 1. Experimental Principles and Methods Example 1 The volt-ampere method was used to measure the resistance of a small bulb with a nominal voltage of 2.5 volts when it was normally lit. (1) In an unfinished circuit (Figure 1), the wire connector M should be connected to a sliding rheostat. __ on the binding post. (2) after the closing of the key K, the indication of the voltmeter is 0.5 volts. To make the small light bulb glow normally, the slide P should move towards __. (3) When the small light bulb emits light normally, ampere The number shown in Figure 2 is __