题目内容
如图所示,静止的电子在加速电压为U1的电场作用下从O经P板的小孔射出,又垂直进入平行金属板间的偏转电场(极板长L、极板间距离d),在偏转电压为U2的电场作用下偏转一段距离。现使U1加倍,要想使电子在偏转电场的偏移量不发生变化(调整极板间距离时电子仍能穿出偏转电场),应该:( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250034348952606.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250034348952606.png)
A.仅使U2加倍 |
B.仅使U2变为原来的4倍 |
C.仅使偏转电场板间距离变为原来的0.5倍 |
D.仅使偏转电场板间距离变为原来的2倍 |
AC
试题分析:据题意,带电粒子在加速电场中做加速运动,有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003434910839.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003434942465.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250034349571167.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003434973811.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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