题目内容
如图所示,质子、氘核和α粒子都沿平行板电容器两板中线OO′方向垂直于电场线射入板间的匀强电场,射出后都打在同一个与OO′垂直的荧光屏上,使荧光屏上出现亮点.下列说法中正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241532247501471.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241532247501471.png)
A.若它们射入电场时的速度相等,在荧光屏上将出现3个亮点 |
B.若它们射入电场时的动量相等,在荧光屏上将只出现2个亮点 |
C.若它们射入电场时的动能相等,在荧光屏上将只出现1个亮点 |
D.若它们是由同一个电场从静止加速后射入此偏转电场的,在荧光屏上将只出现1个亮点 |
D
试题分析:根据类平抛运动规律则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241532253591009.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241532254991006.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153225562978.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153225624923.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153225686840.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153226061803.png)
点评:此类题型考察了带电粒子在电场中的偏转,本题通过结合不同初始条件,求出偏转距离与已知量之间的关系,从而判断偏转距离。
![](http://thumb2018.1010pic.com/images/loading.gif)
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