题目内容
(8分)如图所示,一个有界的匀强磁场,磁感应强度B=0.50T,磁场方向垂直于纸面向里,MN是磁场的左边界.在距磁场左边界MN的1.0m处有一个放射源A,内装放射物质
(镭),
发生α衰变生成新核Rn(氡).放在MN左侧的粒子接收器接收到垂直于边界MN方向射出的α粒子,此时接收器位置距直线OA的距离为1m.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241249259203054.gif)
(1)写出Ra的衰变方程;
(2)求衰变后Rn(氡)的速率(质子、中子的质量为1.6×10-27kg,电子电量e=1.6×10-19C).
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124925889377.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124925889377.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241249259203054.gif)
(1)写出Ra的衰变方程;
(2)求衰变后Rn(氡)的速率(质子、中子的质量为1.6×10-27kg,电子电量e=1.6×10-19C).
(1)
(2)对α粒子
动量守恒得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241249259981829.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124925936657.gif)
(2)对α粒子
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124925951531.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124925951507.gif)
动量守恒得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124925982495.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241249259981829.gif)
略
![](http://thumb2018.1010pic.com/images/loading.gif)
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