题目内容
(16分)如图所示,两块相同的金属板正对着水平放置,板间距离为d。当两板间加电压U时,一个质量为m、电荷量为+q的带电粒子,以水平速度v0从A点射入电场,经过一段时间后从B点射出电场,A、B间的水平距离为L,不计重力影响。求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250039151492161.png)
(1)带电粒子从A点运动到B点经历的时间;
(2)带电粒子经过B点时速度的大小;
(3)A、B间的电势差。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250039151492161.png)
(1)带电粒子从A点运动到B点经历的时间;
(2)带电粒子经过B点时速度的大小;
(3)A、B间的电势差。
(1)
;(2)
;(3)
。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003915165399.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250039151961119.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003915414941.png)
试题分析:(1)带电粒子在水平方向做匀速直线运动,
从A点运动到B点经历的时间
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003915430482.png)
(2)带电粒子在竖直方向做匀加速直线运动
板间场强大小
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003915446598.png)
加速度大小
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003915461653.png)
经过B点时粒子沿竖直方向的速度大小vy=at=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003915492819.png)
带电粒子在B点速度的大小v =
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250039151961119.png)
(3)带电粒子从A点运动到B点过程中,根据动能定理得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003915524999.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003915539169.png)
A、B间的电势差UAB=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003915414941.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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