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利用滑动变阻器改变电流、电压是初中电学内容的重点之一,也是中考的必考题型.同学们也常会在滑动变阻器类的电学题中出错,下面结合具体例题进行分类解析.一、保护电表类问题1.电压表并联在定值电阻两端例1如图1所示的电路中,电源电压U=8V且保持不变,R1=6Ω,R2为最大阻值是50Ω的滑动变阻器,电流表的量程为0～0.6A,电压表的量程为0～3V,为了保护电表,滑动变阻器R2接入电路的阻值变化范围应是多少?
The use of sliding rheostat to change the current, the voltage is one of the focus of the junior high school electrical content, but also the exam will be the exam questions. Students often slide in the rheostat electrical problems in error, the following combination of specific examples for classification analysis. Problem 1. Voltmeter connected in parallel at both ends of the setting resistor Example 1 As shown in Figure 1, the supply voltage U = 8V and remains unchanged, R1 = 6Ω, R2 is the maximum resistance is 50Ω sliding rheostat, the ammeter Range of 0 ~ 0.6A, voltmeter range of 0 ~ 3V, in order to protect the meter, sliding rheostat R2 access circuit resistance range should be changed?