题目内容
如图所示,水平放置的平行金属板之间电压大小为U,距离为d,其间还有垂直纸面向里的匀强磁场.质量为
带电量为+q的带电粒子,以水平速度v0从平行金属板的正中间射入并做匀速直线运动,然后又垂直射入场强大小为E2,方向竖直向上的匀强电场,其边界a、b间的宽为L(该电场竖直方向足够长).电场和磁场都有理想边界,且粒子所受重力不计,求:
(1)匀强磁场对该带电粒子作用力的大小f;
(2)该带电粒子在a、b间运动的加速度大小a;
(3)该带电粒子到达边界b时的速度大小v.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241905572259074.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190556959337.png)
(1)匀强磁场对该带电粒子作用力的大小f;
(2)该带电粒子在a、b间运动的加速度大小a;
(3)该带电粒子到达边界b时的速度大小v.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241905572259074.jpg)
(1)
(2)
(3)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241905578331097.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190557240665.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190557537687.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241905578331097.png)
试题分析:(1)该粒子受力如图
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190558098619.png)
场强:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190558410621.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190558691542.png)
根据平衡条件:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190559003444.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190557240665.png)
(2)电场力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190559533553.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190559783602.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190557537687.png)
(3)粒子在a、b间运动时间:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190600407516.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190600688502.png)
粒子到达边界b时的速度:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190600984639.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241905578331097.png)
点评:做此类型题目的关键是对粒子受力分析,根据牛顿第二定律和曲线运动知识分析解题
![](http://thumb2018.1010pic.com/images/loading.gif)
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