题目内容
如图所示,A和B是置于真空中的两平行金属板,所加电压为U。一带负电的粒子以初速度v0由A板小孔水平射入电场中,粒子刚好能达到金属板B。如果要使粒子刚好达到两板间距离的一半处,可采取的办法有:( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250014342541550.jpg)
A、初速度为v0/2,电压U不变 B、初速度为v0/2,电压为U/2
C、初速度为v0,电压为2U D、初速度为v0,电压为![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434270478.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250014342541550.jpg)
A、初速度为v0/2,电压U不变 B、初速度为v0/2,电压为U/2
C、初速度为v0,电压为2U D、初速度为v0,电压为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434270478.png)
BC
试题分析:粒子刚好能达到B金属板时,根据动能定理得,
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434285908.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434301442.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434317312.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434317312.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434285908.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434301442.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434395451.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434285908.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434441343.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434285908.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434270478.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001434566427.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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