题目内容
(1)粒子由孔
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115549304219.gif)
(2)粒子进入偏转分离器后在洛伦兹力作用下做圆周运动,在照相底片MN上的D点形成感光条纹,测得D点到
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115549304219.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241155494281856.gif)
(1)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115549460584.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115549444318.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115549460584.gif)
(1)粒子在
间做匀速直线运动,所以粒子受电场力
和磁场力大小相等,方向相反,即
-------------3分
由此解出粒子进入偏转分离器时的速度为
------------------2分
(2)粒子进入偏转分离器的磁场后做匀速圆周运动,洛伦兹力提供向心力,即
--------------------- 3分
由此解出粒子运动的圆周半径为
将(1)中求出的v代入上式,并由题意
------------------ 1分
得出:
--------------------------- 3分
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115549475254.gif)
和磁场力大小相等,方向相反,即
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115549522458.gif)
由此解出粒子进入偏转分离器时的速度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115549444318.gif)
(2)粒子进入偏转分离器的磁场后做匀速圆周运动,洛伦兹力提供向心力,即
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115549553523.gif)
由此解出粒子运动的圆周半径为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115549569479.gif)
将(1)中求出的v代入上式,并由题意
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115549631373.gif)
得出:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115549460584.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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