题目内容
如图电路是将滑动变阻器作分压器用的电路,A、B为分压器的输出端,若把变阻器的滑动滑片P放在变阻器中央,下列判断中正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018115312633.jpg)
A. 空载时输出电压为![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001811547709.png)
B. 当接上负载R时,输出电压为![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001811563734.png)
C. 负载电阻R的阻值越大,UAB越接近![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001811594553.png)
D. 负载电阻R的阻值越小,UAB越接近![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001811594553.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018115312633.jpg)
A. 空载时输出电压为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001811547709.png)
B. 当接上负载R时,输出电压为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001811563734.png)
C. 负载电阻R的阻值越大,UAB越接近
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001811594553.png)
D. 负载电阻R的阻值越小,UAB越接近
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001811594553.png)
ABC
试题分析:空载时,滑动变阻器上、下两部分串联,又因P在变阻器中央,所以上、下部分电阻相等,故电压相等,所以A正确;当接上负载时,变阻器下半部分与R并联,并联后总阻值小于上半部分的阻值,所以电压
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001811563734.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001811594553.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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