题目内容
如图所示,一个质量为
、电荷量
带正电的小球,用绝缘细线悬于竖直放置的足够大的平行金属板中的O点,已知两板相距
。合上开关后,小球静止时细线与竖直方向的夹角为
,电源电动势
,内阻
,电阻
,
。G取
。求:
(1)通过电源的电流强度;
(2)夹角
的大小。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241151187994752.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118643530.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118659482.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118674416.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118674201.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118690404.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118721387.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118737311.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118752566.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118768411.gif)
(1)通过电源的电流强度;
(2)夹角
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118674201.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241151187994752.jpg)
⑴1A;⑵37°
(1)
与
并联后的电阻值
(2分)
由闭合电路欧姆定律得:
(2分)
(2)电容器两板间的电场强度
(2分)
小球处于静止状态,由平衡条件得:
(2分)
代入数据解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118815224.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118830222.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118846714.gif)
由闭合电路欧姆定律得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118862630.gif)
(2)电容器两板间的电场强度
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118893714.gif)
小球处于静止状态,由平衡条件得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118908550.gif)
代入数据解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115118908593.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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