题目内容
(12分) 如图所示,有界匀强磁场的磁感应强度B=2×10-3 T;磁场右边是宽度L=0.2 m、场强E=40 V/m、方向向左的匀强电场.一带电粒子电荷量q=-3.2×10-19 C,质量m=6.4×10-27 kg,以v=4×104 m/s的速度沿OO′垂直射入磁场,在磁场中偏转后进入右侧的电场,最后从电场右边界射出.(不计重力)求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250024205503226.png)
(1)大致画出带电粒子的运动轨迹;
(2)带电粒子在磁场中运动的轨道半径;
(3)带电粒子飞出电场时的动能Ek.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250024205503226.png)
(1)大致画出带电粒子的运动轨迹;
(2)带电粒子在磁场中运动的轨道半径;
(3)带电粒子飞出电场时的动能Ek.
(1)0.4m;(2)如下图;(3)7.68×10?18J.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500242069118158.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500242069118158.png)
试题分析:(1)粒子运动轨迹如图。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500242070620390.png)
(2)带电粒子在磁场中运动时洛仑兹力做向心力,
则
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002420722763.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250024207371679.png)
(3)根据动能定理,粒子在射出电场过程中
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002420753725.png)
代人数据解得:EK’=7.68×10?18J
![](http://thumb2018.1010pic.com/images/loading.gif)
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