题目内容
如图8-2-23所示,匀强磁场中有一个电荷量为q的正离子,自a点沿半圆轨道运动,当它运动到b点时,突然吸收了附近若干电子,接着沿另一半圆轨道运动到c点,已知a、b、c在同一直线上,且
,电子电荷量为e,电子质量可忽略不计.则该离子吸收的电子个数为( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241209359181958.jpg)
图8-2-23
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120935918366.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241209359181958.jpg)
图8-2-23
A.![]() | B.![]() | C.![]() | D.![]() |
D
离子在洛伦兹力的作用下做匀速圆周运动,其半径
.离子碰上电子后半径变为
,所以
,离子的电荷量减少了
,故吸附的电子个数
,选项D正确.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120936027489.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120936043626.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120936074436.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120936089256.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120936089566.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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