题目内容
下图所示的电路中,电源电动势E=6V,内阻
,电阻
,
,电容器的电容
,二极管D具有单向导电性,开始时,开关S1闭合,S2断开。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241154270603289.jpg)
(1)合上S2,待电路稳定以后,求电容器C上电荷量变化了多少?
(2)合上S2,待电路稳定以后再断开S1,求断开S1后流过R1的电荷量是多少?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115426998272.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427014313.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427029321.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427029457.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241154270603289.jpg)
(1)合上S2,待电路稳定以后,求电容器C上电荷量变化了多少?
(2)合上S2,待电路稳定以后再断开S1,求断开S1后流过R1的电荷量是多少?
(1)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427092859.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427076786.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427092859.gif)
(1)设开关S1闭合,S2断开时,电容两端的电压为U1,干路电流为I1
根据闭合电路欧姆定律有
①
②
合上开关S2后,电容电压为U2,干路电流为I2
根据闭合电路欧姆定律有
③
④
所以电容器上电荷量变化了
⑤
(或电容器上电荷量减少了
)
(2)合上S2后,电容上电荷量为
⑥
断开S1后,R1和R2的电流与阻值成反比,故流过的电荷量与阻值成反比
故流过R1的电荷量
⑦
根据闭合电路欧姆定律有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427107603.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427123266.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427138334.gif)
合上开关S2后,电容电压为U2,干路电流为I2
根据闭合电路欧姆定律有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427154789.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427170733.gif)
所以电容器上电荷量变化了
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427076786.gif)
(或电容器上电荷量减少了
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427232784.gif)
(2)合上S2后,电容上电荷量为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427263216.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427279651.gif)
断开S1后,R1和R2的电流与阻值成反比,故流过的电荷量与阻值成反比
故流过R1的电荷量
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115427092859.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目