题目内容
(14分)如图所示,倾角为
的光滑导轨上端接入一定值电阻,Ⅰ和Ⅱ是边长都为L的两正方形磁场区域,其区域内的磁场方向都垂直于导轨平面向上,区域Ⅰ中磁场的磁感强度为
,区域Ⅱ中磁场随时间按
变化,一质量为
、电阻为
的金属杆穿过区域Ⅰ垂直地跨放在两导轨上,并恰能保存静止。试求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250011546047666.png)
(1)通过金属杆的电流大小;
(2)定值电阻的阻值为多大?
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001154510310.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001154526337.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001154541516.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001154557337.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001154572260.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250011546047666.png)
(1)通过金属杆的电流大小;
(2)定值电阻的阻值为多大?
(1)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250011546821055.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001154635871.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250011546821055.png)
试题分析:(1)对金属杆:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001154697783.png)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001154635871.png)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250011547441087.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001154775616.png)
故:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250011547911249.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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