逸枫凌凌
幼苗
共回答了13个问题采纳率:100% 举报
![](https://img.yulucn.com/upload/e/81/e81cab029120de7f5a73d7a5e6803211_thumb.jpg)
如图所示,磁感应强度大小 B= 0.15T,方向垂直纸面向里的匀强磁场分布在半径为 R =0.10m的圆形区域内,圆的左端跟
![](https://img.yulucn.com/upload/7/b1/7b1bb1324f396e3c683539f76fe84ec9_thumb.jpg)
轴相切于直角出标系的原点
![](https://img.yulucn.com/upload/a/9e/a9ef675647c172ba31725d14ce17e3ba_thumb.jpg)
,右端边界 MN 相切于
![](https://img.yulucn.com/upload/4/02/402b9e4fb970ce2e848a21e98772dbd6_thumb.jpg)
轴的 A 点。 MN 右侧有方向平行于
![](https://img.yulucn.com/upload/4/02/402b9e4fb970ce2e848a21e98772dbd6_thumb.jpg)
轴负方向的匀强电场。置于原点
![](https://img.yulucn.com/upload/a/9e/a9ef675647c172ba31725d14ce17e3ba_thumb.jpg)
的粒子源,可沿
![](https://img.yulucn.com/upload/4/02/402b9e4fb970ce2e848a21e98772dbd6_thumb.jpg)
轴正方向射出速度
![](https://img.yulucn.com/upload/a/9d/a9d4766d0ede6c7a15bfeb907d6ffed4_thumb.jpg)
的带正电的粒子流,荷质比
![](https://img.yulucn.com/upload/c/be/cbeae6085c50090def9e9cc35e405dcc_thumb.jpg)
,粒子重力不计。右侧场强大小
![](https://img.yulucn.com/upload/f/06/f06641109feb78f42e8900e5f67c667f_thumb.jpg)
。现以过
![](https://img.yulucn.com/upload/a/9e/a9ef675647c172ba31725d14ce17e3ba_thumb.jpg)
点并垂直于纸面的直线为轴,将圆形磁场区域按逆时针方向缓慢旋转90°。
![](https://img.yulucn.com/upload/e/81/e81cab029120de7f5a73d7a5e6803211_thumb.jpg)
(1)带电粒子在磁场中的运动半径
![](https://img.yulucn.com/upload/8/ed/8ed5978c3ac4b3058a7f95e397a02353_thumb.jpg)
;
![](https://img.yulucn.com/upload/e/81/e81cab029120de7f5a73d7a5e6803211_thumb.jpg)
(2)此过程中粒子经过磁场后,途经 MN 进入电场,求:粒子经过 MN 时离 A 点最远的
![](https://img.yulucn.com/upload/e/81/e81cab029120de7f5a73d7a5e6803211_thumb.jpg)
位置 B 到 A 点的距离
![](https://img.yulucn.com/upload/d/e3/de308c9bfe9ece840cbcacb6fad7fa1b_thumb.jpg)
;
![](https://img.yulucn.com/upload/e/81/e81cab029120de7f5a73d7a5e6803211_thumb.jpg)
(3)通过 B 点的粒子进入电场后,再次经过 MN 时距 B 点的距离
![](https://img.yulucn.com/upload/5/0a/50a0eef466f73c56131e8002efb486d1_thumb.jpg)
为多大?
(1)0.2m (2)0.15m (3)0.39m
(1)由洛伦兹力等于向心力,设粒子做圆周运动的半径为
![](https://img.yulucn.com/upload/8/ed/8ed5978c3ac4b3058a7f95e397a02353_thumb.jpg)
;
![](https://img.yulucn.com/upload/e/81/e81cab029120de7f5a73d7a5e6803211_thumb.jpg)
即:
![](https://img.yulucn.com/upload/e/81/e81cab029120de7f5a73d7a5e6803211_thumb.jpg)
得
![](https://img.yulucn.com/upload/e/81/e81cab029120de7f5a73d7a5e6803211_thumb.jpg)
(2)当圆形磁场逆时针旋转到直径
![](https://img.yulucn.com/upload/6/86/686c2879ea316e724b9cd02f38e638fd_thumb.jpg)
与
![](https://img.yulucn.com/upload/4/02/402b9e4fb970ce2e848a21e98772dbd6_thumb.jpg)
轴方向夹角为
![](https://img.yulucn.com/upload/f/40/f407d4286d1c6975d36956bbc58ed4cf_thumb.jpg)
时,粒子经过
![](https://img.yulucn.com/upload/5/9a/59a19ac58d236ecdfb9e08039ef6955c_thumb.jpg)
上
![](https://img.yulucn.com/upload/d/96/d96568fec5323b86ec7dd52bc8eebbf0_thumb.jpg)
点时离
![](https://img.yulucn.com/upload/3/7d/37d579a1043c5fbd585f39039a71e598_thumb.jpg)
最远,如图所示,
![](https://img.yulucn.com/upload/e/81/e81cab029120de7f5a73d7a5e6803211_thumb.jpg)
由图知:
![](https://img.yulucn.com/upload/e/81/e81cab029120de7f5a73d7a5e6803211_thumb.jpg)
设
![](https://img.yulucn.com/upload/d/96/d96568fec5323b86ec7dd52bc8eebbf0_thumb.jpg)
到
![](https://img.yulucn.com/upload/3/7d/37d579a1043c5fbd585f39039a71e598_thumb.jpg)
的距离为
![](https://img.yulucn.com/upload/d/e3/de308c9bfe9ece840cbcacb6fad7fa1b_thumb.jpg)
;
得
![](https://img.yulucn.com/upload/e/81/e81cab029120de7f5a73d7a5e6803211_thumb.jpg)
(3)粒子经过
![](https://img.yulucn.com/upload/d/96/d96568fec5323b86ec7dd52bc8eebbf0_thumb.jpg)
点时速度与
![](https://img.yulucn.com/upload/5/9a/59a19ac58d236ecdfb9e08039ef6955c_thumb.jpg)
夹角
![](https://img.yulucn.com/upload/e/3b/e3b07d5cf2376d388d15a9a0132e3049_thumb.jpg)
,则:
![](https://img.yulucn.com/upload/e/81/e81cab029120de7f5a73d7a5e6803211_thumb.jpg)
粒
1年前
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