题目内容
(10分)如图所示,一条长为
的细线,上端固定,下端拴一质量为 m的带电小球,将它置于一匀强电场中,电场强度大小为E,方向水平向右,当细线离开竖直位置的偏角为θ时,小球处于平衡,则小球带何种电荷?小球所
带电量为多少?![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241213030243239.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121302977185.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412130299372.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241213030243239.jpg)
小球带正电荷,![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241213030391641.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241213030391641.jpg)
小球在匀强电场中受力如图,(2分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241213030552550.jpg)
电场力水平向右,与场强方向相同。因此小球带正电荷。(3分)
由平衡条件,知
…………………(3分)
小球的带电量
……………………(2分)
没有作图但过程和结果正确不扣分
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241213030552550.jpg)
电场力水平向右,与场强方向相同。因此小球带正电荷。(3分)
由平衡条件,知
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241213030711949.jpg)
小球的带电量
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241213030391641.jpg)
没有作图但过程和结果正确不扣分
![](http://thumb2018.1010pic.com/images/loading.gif)
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