题目内容
(6分)如图所示为一种改进后的回旋加速器示意图。半径为
的两个中空D形盒,处于垂直于盒面向里、磁感应强度为
的匀强磁场中。两D形盒左端狭缝处放置一场强恒定的加速电场。带电粒子从
处以速度
沿电场线方向射入加速电场,经加速后再进入D形盒中的匀强磁场做匀速圆周运动,接着又从
处进入
、
板间,如此反复,最后从D形盒右侧的边缘飞出。对于这种改进后的回旋加速器,带电粒子每运动一周被加速 次。若被加速的带电粒子的电荷量为
,质量为
,则粒子的最大速度的表达式为 。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241543349126602.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154333804303.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154333914309.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154334054346.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154334163322.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154334054346.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154334491300.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154334600313.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154334694310.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154334772337.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241543349126602.jpg)
1、![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154335084600.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154335084600.png)
试题分析:带电粒子在电场外运动时,电场方向不用改变,带电粒子每运动一周被加速 一次;当粒子从D形盒中出来时,速度最大,此时运动的半径等于D形盒的半径,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241543352081124.png)
点评:解决本题的关键知道当粒子从D形盒中出来时,速度最大.以及知道回旋加速器粒子在磁场中运动的周期和高频交流电的周期相等.
![](http://thumb2018.1010pic.com/images/loading.gif)
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