题目内容
如图所示的圆形区域里,匀强磁场的方向是垂直于纸面向内,有一束速率各不相同的质子自A点沿半径方向射入磁场,不计质子的重力,这些质子在磁场中:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241552509443366.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241552509443366.png)
A.运动时间越长,其轨迹对应的圆心角越大 |
B.运动时间越长,其轨迹越长 |
C.运动时间越短,射出磁场区域时速度越小 |
D.运动时间越短,射出磁场区域时速度的偏向角越大 |
A
试题分析:根据公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155251084769.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155251209760.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155251365686.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155251521364.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155251661640.png)
点评:本题关键是对公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155251084769.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155251209760.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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