题目内容
如图4所示,足够长的光滑U型导轨宽度为L,其所在平面与水平面的夹角为 ![]() ![]() ![]() ![]() ![]()
|
B
感应电动势为
①
感应电流为
②
安培力为
③
根据平恒条件得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132808281731.png)
解得:
由能量守恒定律得:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241328083591122.png)
又因![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132808390735.png)
所以![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241328085611441.png)
由法拉第电磁感应定律得通过R的电量为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132808655955.png)
所以选项B正确
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132807922555.png)
感应电流为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132808156616.png)
安培力为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132808203931.png)
根据平恒条件得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132808281731.png)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241328083271230.png)
由能量守恒定律得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241328083591122.png)
又因
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132808390735.png)
所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241328085611441.png)
由法拉第电磁感应定律得通过R的电量为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132808655955.png)
所以选项B正确
![](http://thumb2018.1010pic.com/images/loading.gif)
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