题目内容
如图所示为多用表欧姆挡的原理示意图,其中电流表的满偏电流为300 μA,内阻rg=100 Ω,调零电阻最大阻值R=50 kΩ,串联的固定电阻R0=50 Ω,电池电动势E=1.5 V,用它测量电阻Rx,能准确测量的阻值范围是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241621153093621.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241621153093621.jpg)
A.30 kΩ~80 kΩ |
B.3 kΩ~8 kΩ |
C.300 kΩ~800 kΩ |
D.3000 kΩ~8000 kΩ |
B
试题分析:欧姆表能准确测量的阻值范围是是量程的
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824162115418327.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824162115559382.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824162115824785.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824162115964873.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824162116276643.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824162116744897.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824162117041695.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824162117322355.png)
故选B
点评:使用欧姆表时要合理选择量程,使指针尽可能在中间刻度附近,参考指针偏转在
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824162117571446.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824162117883423.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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