题目内容
如图所示,矩形MNPQ区域内有方向垂直于纸面的匀强磁场,有5个带点粒子从图中箭头所示位置垂直于磁场边界进入磁场,在纸面内做匀速圆周运动,运动轨迹为相应的圆弧,这些粒子的质量,电荷量以及速度大小如下表所示。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082413225203736356.png)
由以上信息可知,从图中abc处进入的粒子对应表中的编号分别为( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082413225203736356.png)
由以上信息可知,从图中abc处进入的粒子对应表中的编号分别为( )
A.3,5, 4 | B.4,2,5 | C.5,3,2 | D.2,4,5 |
D
粒子在磁场中受到的洛伦兹力充当向心力,所以
即
,从图中设
,则1号为
,
,
,
,
。可知从a处和从b处进入的粒子的电荷种类相同,并且半径之比为
,a和c处进入的粒子电荷种类相反,半径相同,故可判断出abc处进入的粒子编号为2,4,5.D正确。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132252068764.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132252099671.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132252130636.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132252162471.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132252193434.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132252224428.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132252255411.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132252286437.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132252318623.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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