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来源：学生作业帮助网 编辑：作业帮 时间：2024/04/27 11:07:45
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开关接电流表0.6接线柱,电压表“-”接滑动变阻器右下接线柱
刚闭合开关时,滑动变阻器阻值为50Ω,根据2V,0.2A
可求滑动变阻器两端电压U1=I1R=0.2A*50Ω=10V
电源电压U=10V+2V=12V
当灯正常工作,电流为0.3A,滑动变阻器的电阻为25Ω
滑动变阻器两端电压U2=IR2=7.5V
灯的额定电压U灯=12V-7.5V=4.5V
灯的额定功率P=U灯I=1.35W
注意：灯的电阻是变化的,正常工作时不能使用2V时的电阻

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