如图,边界OA与OC之间有垂直纸面向里的匀强磁场,边界OA上S处有一粒子源。某一时刻,从粒子源平行于纸面向各个方向以相同速率发射出大量的同种带正电粒子。已知O、S两点间的距离为a,∠AOC=60°,磁感应强度大小为B,粒子比荷为
,从OC边界射出的粒子在磁场中运动的最短时间为
,不计重力及粒子间的相互作用,则粒子的速率为( )
![](https://img.xkw.com/dksih/QBM/2021/1/29/2646521187950592/2647141937291264/STEM/e60c1f69-4a4c-4a90-9a67-f86f761e284b.png?resizew=139)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9da659de03afffb155aaa89e6d1f7e70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85bb8ec2af7191bf27d4808e8cf785d8.png)
![](https://img.xkw.com/dksih/QBM/2021/1/29/2646521187950592/2647141937291264/STEM/e60c1f69-4a4c-4a90-9a67-f86f761e284b.png?resizew=139)
A.![]() | B.![]() | C.![]() | D.![]() |
更新时间:2021-01-30 10:06:58
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【知识点】 带电粒子在直边界磁场中运动
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【推荐1】如图所示,MN是磁感应强度为B的匀强磁场的边界。一质量为m、电荷量为q的粒子在纸面内从O点射入磁场。若粒子速度为v0,最远能落在边界上的A点。下列说法正确的有( )
![](https://img.xkw.com/dksih/QBM/2022/5/29/2989959226941440/2990794722009088/STEM/ca9381a5cde44bcabc803e9d02e53280.png?resizew=188)
![](https://img.xkw.com/dksih/QBM/2022/5/29/2989959226941440/2990794722009088/STEM/ca9381a5cde44bcabc803e9d02e53280.png?resizew=188)
A.若粒子落在A点的左侧,其速度一定小于v0 |
B.若粒子落在A点的右侧,其速度一定等于v0 |
C.若粒子落在A点左右两侧d的范围内,其速度不可能小于![]() |
D.若粒子落在A点左右两侧d的范围内,其速度不可能大于![]() |
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【推荐2】如图所示,在边界
上方有磁感应强度大小为
、方向垂直纸面向外的匀强磁场,
距离为
,
是一足够长的挡板,
延长线与
的夹角为
,粒子打在挡板上均被吸收。在
、
之间有大量质量、电荷量和速度都相同的粒子,速度方向均垂直于边界
,且在纸面内。其中从
中点射入的粒子恰能垂直打在挡板上(不计粒子重力及其相互作用,
,
)。则下列说法正确的是( )
![](https://img.xkw.com/dksih/QBM/2020/12/31/2626215066746880/2627666890227712/STEM/4c4d9db7-96b7-48da-b5a3-027d73279e50.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abd13974aebe38eb2a1d744a01ea5aa5.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abd13974aebe38eb2a1d744a01ea5aa5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
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![](https://img.xkw.com/dksih/QBM/2020/12/31/2626215066746880/2627666890227712/STEM/4c4d9db7-96b7-48da-b5a3-027d73279e50.png)
A.当![]() ![]() |
B.当![]() ![]() |
C.当![]() ![]() |
D.当![]() ![]() |
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