题目内容
(8分)如图所示,面积为0.2m2的100匝线圈A处在磁场中,磁场方向垂直于线圈平面.磁感强度随时间变化的规律是B=(6-0.2t) (T)已知R1=4Ω,R2=6Ω,电容C=30μF,线圈A的电阻不计.求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250020077673109.jpg)
(1)闭合S后,通过R2的电流强度大小和方向。
(2)闭合S一段时间后在断开S,S断开后通过R2的电荷量是多少?
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250020077673109.jpg)
(1)闭合S后,通过R2的电流强度大小和方向。
(2)闭合S一段时间后在断开S,S断开后通过R2的电荷量是多少?
(1)0.4A 电流方向由
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002007814617.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002007798577.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002007814617.png)
试题分析:(1)由题意
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002007814665.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002007830838.png)
由法拉第电磁感应定律知:A线圈内产生的感应电动势:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250020078451607.png)
S闭合后,电路中电流由闭合电路欧姆定律
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250020078611197.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002007798577.png)
(2)S闭合后R2的电压为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002007892528.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250020079081085.png)
所以断开S后,电容器开始放电,通过R2的电荷量
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002007923736.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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