题目内容
通有电流i=Imsinωt的长直导线OO′与断开的圆形导线圈在同一平面内,如图6所示(设电流由O至O′为正),为使A端的电势高于B端的电势且UAB减小,交变电流必须处于每个周期的 ( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241416057214355.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241416057214355.jpg)
A.第一个![]() | B.第二个![]() |
C.第三个![]() | D.第四个![]() |
A
由E∝
∝
可知,要E减小,即要
减小,题中要求φA>φB,由楞次定律知,只有在第一个
周期才符合要求,A项正确.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141606080508.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141606127502.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141606361467.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141605737303.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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