题目内容
如图所示,宽为0.5m的光滑水平金属框架固定在方向竖直向下、磁感应强度大小为
的匀强磁场中,框架左端连接一个
的电阻,框架上面置一电阻
的金属导体
,
长为
。
始终与框架接触良好且在水平恒力
作用下以
的速度向右匀速运动(设水平金属框架足够长。轨道电阻及接触电阻忽略不计)。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241323170445017.png)
(1)试判断金属导体
两端哪端电势高;
(2)求通过金属导体
的电流大小;
(3)求水平恒力
对金属导体
做功的功率。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316669559.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316700547.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316732521.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316778380.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316778380.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316872479.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316778380.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316966303.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316997666.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241323170445017.png)
(1)试判断金属导体
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316778380.png)
(2)求通过金属导体
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316778380.png)
(3)求水平恒力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316966303.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316778380.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132317231287.png)
(1)ab棒切割磁感线产生感应电动势,充当电源,根据右手定则可知a端电势较高
(2)感应电动势
,通过金属导体
的电流大小![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241323173561049.png)
(3)ab棒做匀速运动,所以水平恒力与安培力平衡,即
,水平恒力
对金属导体
做功的功率![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132317512959.png)
故答案为:
, 1A, 0.5W
(2)感应电动势
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241323172621053.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316778380.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241323173561049.png)
(3)ab棒做匀速运动,所以水平恒力与安培力平衡,即
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241323174181014.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316966303.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132316778380.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132317512959.png)
故答案为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132317231287.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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