在测小灯泡电功率或电阻的实验中，实验器材完好无缺，但经常碰到下列几种不正常现象，请分析原因，并排除之．实验电路如图1所示．（1）闭合开关后，灯泡发出强光，但瞬间灯丝断裂，电路不工作，示数为零，示数很大．分析（1）变阻器R0接入电路的电阻太小，灯泡两端的电压远大 In the experiment of measuring the electric power or resistance of the light bulb, the experimental equipment is intact, but often encountered the following kinds of abnormal phenomena, please analyze the reasons and eliminate it. The experimental circuit is shown in Figure 1. (1) After the switch is closed, the light bulb emits strong light, but the filament is momentarily broken, the circuit does not work, the number of indications is zero, and the number of indications is large. Analysis (1) The resistance of the varistor R0 access circuit is too small and the voltage across the lamp bulb is very large