题目内容
(14分)如图所示,图中左边有一对平行金属板,两板相距为d,电压为U。两板之间有匀强磁场,磁感应强度大小为B0,方向与金属板面平行并垂直于纸面朝里;图中右边有一半径为R、圆心为O的圆形区域,区域内也存在匀强磁场,磁感应强度大小为B,方向垂直于纸面朝里。一电荷量为q的正离子沿平行于金属板面、垂直于磁场的方向射入平行金属板之间,沿同一方向射出平行金属板之间的区域,并沿直径PQ方向射入磁场区域,最后从圆形区域边界上的G点射出,已知弧QG所对应的圆心角为
。离子重力不计。求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250031515786006.jpg)
(1)离子速度的大小;
(2)离子在圆形磁场区域内做圆周运动的半径;
(3)离子的质量。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003151563297.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250031515786006.jpg)
(1)离子速度的大小;
(2)离子在圆形磁场区域内做圆周运动的半径;
(3)离子的质量。
(1)
(2)
(3)![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250031516251186.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003151594692.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003151609683.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250031516251186.png)
试题分析:(1)粒子匀速运动
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003151641642.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003151656592.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003151594692.png)
(2)由几何关系可知
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003151687704.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003151609683.png)
(3)由
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003151719761.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250031516251186.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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