题目内容
如图所示,接通开关S的瞬间,用丝线悬挂于一点可自由转动的通电直导线AB将( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241209412382579.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241209412382579.jpg)
A.A端向上,B端向下,悬线张力不变 |
B.A端向下,B端向上,悬线张力不变 |
C.A端向纸外,B端向纸内,悬线张力变小 |
D.A端向纸内,B端向纸外,悬线张力变大 |
D
当开关S接通时,据安培定则知电磁铁附近磁感线分布如图,由左手定则判断出通电直导线此时左部受力指向纸内,右部受力指向纸外,导线将转动,转到与磁感线接近垂直时,整个导线受磁场力将竖直向下,可知悬线张力变大,故D选项正确.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241209412533058.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241209412533058.jpg)
![](http://thumb2018.1010pic.com/images/loading.gif)
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