题目内容
如图所示,一电荷量为q,质量为m的带正电粒子,经过水平方向的加速电场U,沿水平方向进入竖直方向的偏转电场U2,已知粒子从偏转电场下极板最左端的G点进入,恰从上极板最右端A点离开偏转电场,立即垂直射入一圆形区域的均强磁场内,AC是圆形磁场区域的一条沿水平方向的直径。粒子速度方向与AC成
角,已知圆形区域的直径为D、磁感应强度为B,磁场方向垂直于圆平面指向外,
,若此粒子在磁场区域运动过程中,速度的方向一共改变了
,重力忽略不计,侧下列说法正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250052059317440.png)
A.粒子在磁场中运动速度大小为![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005205962777.png)
B.该粒子在磁场中运动的时间为![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005205978619.png)
C.偏离电场的板间距为d和板长L的比值![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005205993756.png)
D. 加速电场和偏转电场所加电压比![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206009842.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005205869457.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005205884681.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005205900373.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250052059317440.png)
A.粒子在磁场中运动速度大小为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005205962777.png)
B.该粒子在磁场中运动的时间为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005205978619.png)
C.偏离电场的板间距为d和板长L的比值
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005205993756.png)
D. 加速电场和偏转电场所加电压比
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206009842.png)
ABD
试题分析:设粒子在磁场中圆周运动的半径为r.画出其运动轨迹如图,由几何知识得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500520602510837.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250052060401770.png)
则
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206056951.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206071761.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206087866.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250052061031388.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206134350.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206149322.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206165842.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206181816.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206196780.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206212836.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206227860.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206181816.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005206259830.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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