题目内容
由于科学研究的需要,常常将质子和α粒子等带电粒子贮存在圆环状空腔中,圆环状空腔置于一个与圆环平面垂直的匀强磁场中,磁感应强度为B.如果质子和α粒子在空腔中做圆周运动的轨迹相同(如图中虚线所示),磁场也相同,比较质子和α粒子在圆环状空腔中运动的动能EkH和Ekα及周期TH和Tα的大小,有( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241258382863145.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241258382863145.png)
A.EkH≠Ekα,TH≠Tα | B.EkH=Ekα,TH=Tα | C.EkH≠Ekα,TH=Tα | D.EkH=Ekα,TH≠Tα |
BD
根据洛伦兹力提供向心力可得
,则运动动能
,质子![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125838348349.png)
α粒子
,可知动能相等,周期
由于两粒子比荷不同,所以周期不同,即EkH=Ekα,TH≠Tα,选D
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125838317748.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125838333945.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125838348349.png)
α粒子
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125838364431.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824125838379775.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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