题目内容
如图,在竖直面内有两平行金属导轨AB、CD。导轨间距为L,电阻不计。一根电阻不计的金属棒
可在导轨上
无摩擦地滑动。棒与导轨垂直,并接触良好。导轨之间有垂直纸面向外的匀强磁场,磁感强度为B。导轨右边与电路连接。电路中的两个定值电阻组织分别为2R和R。在BD间接有一水平放置的平行板电容器C,板间距离为d。当![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412293513965.gif)
以速度
匀速向左运动时,电容器中质量为m的带电微粒恰好静止。求:微粒的带电性质,及带电量的大小。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241229351864273.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122935108223.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412293512372.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412293513965.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122935108223.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122935154204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241229351864273.jpg)
棒匀速向左运动
,感应电流为顺时针方向,电容器上板带正电。
∵微粒受力平衡,电场力方向向上,场强方向向下
∴微粒带负电
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122935217297.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122935248426.gif)
由以上各式求出![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122935264589.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412293518672.gif)
∵微粒受力平衡,电场力方向向上,场强方向向下
∴微粒带负电
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122935201509.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122935217297.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122935232320.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122935248426.gif)
由以上各式求出
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122935264589.gif)
略
![](http://thumb2018.1010pic.com/images/loading.gif)
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