题目内容
(10分) 如图所示,电源电动势E=10 V,内阻r=1 Ω,R1=3 Ω,R2=6 Ω,C=30 μF.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250031259161374.png)
(1)闭合开关S,求稳定后通过R1的电流;
(2)然后将开关S断开,求电容器两端的电压变化量和断开开关后流过R1的总电量;
(3)如果把R2换成一个可变电阻,其阻值可以在0~10 Ω范围变化,求开关闭合并且电路稳定时,R2消耗的最大电功率.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250031259161374.png)
(1)闭合开关S,求稳定后通过R1的电流;
(2)然后将开关S断开,求电容器两端的电压变化量和断开开关后流过R1的总电量;
(3)如果把R2换成一个可变电阻,其阻值可以在0~10 Ω范围变化,求开关闭合并且电路稳定时,R2消耗的最大电功率.
(1)1A(2)
(3)![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003125963570.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003125932582.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003125963570.png)
试题分析:(1)稳定时,电容器看做断开状态,电路中的电流:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250031259781193.png)
(2)S闭合,电路处于稳定状态时,电容器两端的电压
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003125994781.png)
断开开关后,电容器两端的电压为10 V,所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003126010565.png)
流过
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003126041327.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250031260561274.png)
(3)当
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003126088697.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003126103361.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250031261191201.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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