如图,电源的内阻不可忽略。已知定值电阻R1=10Ω,R2=8Ω。当电键S接位置1时,电流表的示数为0.21A。那么当电键S接位置2时,电流表的示数可能是下列的哪些值( )
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/25/9a0145be-4acc-4317-9f04-0c1f98b76b94.png?resizew=160)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/25/9a0145be-4acc-4317-9f04-0c1f98b76b94.png?resizew=160)
A.0.28A | B.0.25A | C.0.22A | D.0.19A |
更新时间:2021-10-23 14:21:44
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【知识点】 闭合电路欧姆定律的内容和三个公式
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【推荐1】如图所示,
、
都是阻值为
的定值电阻,
是阻值足够大的滑动变阻器,电源内阻为
,
、
和
都是理想电压表和电流表;
、
分别表示电压表
、
示数的变化量,
表示电流表
的示数变化量。闭合开关
,当滑动变阻器的滑片由左向右缓慢滑动时,则下列说法中正确的是( )
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/29/8d158d85-3cc7-4958-ad53-8444bd825714.jpg?resizew=195)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efc18a5bb2e53586331b2a58538a48b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19f20f21a9d50b61dac519a3ddab539d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be9b4a83b9aebebf29de0c4406ebf894.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46ad1a9cd19361d1f7a2340d76d50c80.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c688d3183cdee79c0ce7d84a23a38c4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff4489d9b83072184c0e1d6b09be50ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e272451d8d2263734df061afbc715708.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/885544a287ed7bcdcabc867fa0b7e787.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48fade4e14bf5845ff14f9e95bb6bfef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b40f1d184152aa3954752ed70e7d1612.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/596fd2f65c2602cbd49aa23e2c4fc6a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff4489d9b83072184c0e1d6b09be50ca.png)
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![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/29/8d158d85-3cc7-4958-ad53-8444bd825714.jpg?resizew=195)
A.![]() ![]() ![]() |
B.![]() |
C.![]() ![]() |
D.![]() |
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【推荐2】如图所示的电路中,灯泡
分别标有“10V,10W”和“6V,3W”字样,滑动变阻器的最大阻值为10Ω。当开关拨至“1”位置且滑片滑到A端时,灯L1恰好正常发光;当开关拨至“2”位置且滑片滑到B端时,灯L2恰好正常发光。不计灯丝电阻随温度的变化。下列判断正确的是( )
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/20/6463f151-0c80-44a9-b231-3127f856a216.png?resizew=189)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33b3d3e2c547a792fb29523f50b3653e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/20/6463f151-0c80-44a9-b231-3127f856a216.png?resizew=189)
A.电源电动势为12V |
B.电源电动势为9V |
C.电源内阻为1Ω |
D.电源内阻为2Ω |
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