题目内容
(1)求离子在磁场中运动的轨道半径
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610067185.gif)
(2)若离子在磁场中运动的轨道半径为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610067192.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610083187.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610098185.gif)
(3)试推出在
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610114243.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610083187.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610145193.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156101451831.gif)
(1)
(2)
(3)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610208908.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610176475.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610192745.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610208908.gif)
(1)离子进入磁场后,受到洛伦兹力作用,由牛顿第二定律得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156102391663.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156102861360.gif)
……………………………………… (2分)
…………………………………………………… (3分)
(2)如图所示,由几何关系可得,离子进入磁场A点坐标为(
,
)离开磁场B点坐标为(
,
)
由几何关系,离子运动的路程为:
…(3分)
则![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610426678.gif)
或
…………………(2分)
(只要过程分析的思路正确,并列出表达式得出结论的均给分。)
(3)如图所示,设离子运动的轨道半径为
,在
的区域内,令离子离开磁场后与x轴夹角为θ。
由几何关系得:
……………………………………………(2分)
………………(2分)
代入相关数据并化简得:
………… (2分)(只要过
程分析的思路正确,并列出表达式得出结论的均给分。)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156102391663.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241156102861360.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610301530.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610176475.gif)
(2)如图所示,由几何关系可得,离子进入磁场A点坐标为(
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610348247.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610364312.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610379233.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610364312.gif)
由几何关系,离子运动的路程为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610410818.gif)
则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610426678.gif)
或
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610192745.gif)
(只要过程分析的思路正确,并列出表达式得出结论的均给分。)
(3)如图所示,设离子运动的轨道半径为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610067185.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610114243.gif)
由几何关系得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610488429.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610504759.gif)
代入相关数据并化简得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115610208908.gif)
程分析的思路正确,并列出表达式得出结论的均给分。)
![](http://thumb2018.1010pic.com/images/loading.gif)
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