题目内容
质谱仪原理如图所示,a为粒子加速器,电压为U1;b为速度选择器,磁场与电场正交,磁感应强度为B1,板间距离为d;c为偏转分离器,磁感应强度为B2,今有一质量为m,电量为+e的电子(不计重力),经加速后,该粒子恰能通过速度选择器,粒子进入分离器后做半径为R的匀速圆周运动.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082416504082716675.png)
求:(1)粒子的速度v;
(2)速度选择器的电压U2;
(3)粒子在磁感应强度为B2磁场中做匀速圆周运动的半径R.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082416504082716675.png)
求:(1)粒子的速度v;
(2)速度选择器的电压U2;
(3)粒子在磁感应强度为B2磁场中做匀速圆周运动的半径R.
(1)
(2)
(3)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824165041778982.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824165041061786.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241650414511019.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824165041778982.png)
试题分析:(1)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824165042106788.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824165041061786.png)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824165042761749.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241650414511019.png)
(3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824165043260791.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824165041778982.png)
点评:解决本题的关键掌握动能定理,以及知道在速度选择器中作匀速直线运动,电场力与洛仑兹力平衡.
![](http://thumb2018.1010pic.com/images/loading.gif)
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