题目内容
如图所示,相距为l的光滑平行金属导轨ab、cd放置在水平桌面上,阻值为R的电阻与导轨的两端a、c相连。滑杆MN质量为m,垂直于导轨并可在导轨上自由滑动,不计导轨、滑杆以及导线的电阻.整个装置放于竖直方向的范围足够大的匀强磁场中,磁感应强度的大小为B.滑杆的中点系一不可伸长的轻绳,绳绕过固定在桌边的光滑轻滑轮后,与另一质量也为m的物块相连,绳处于拉直状态.现将物块由静止释放,当物块达到最大速度时,物块的下落高度
,用g表示重力加速度,则在物块由静止开始下落至速度最大的过程中
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241326382683965.jpg)
A.物块达到的最大速度是
B.通过电阻R的电荷量是![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132638315860.png)
C.电阻R放出的热量为
D.滑秆MN产生的最大感应电动势为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132638424649.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241326382061013.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241326382683965.jpg)
A.物块达到的最大速度是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132638268753.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132638315860.png)
C.电阻R放出的热量为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132638378940.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132638424649.png)
ABD
最大速度时,
,
,A正确;
,B正确;根据能量有:
,C错误;MN产生的最大感应电动势为
,D正确
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132638487924.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132638534846.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241326385651425.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241326385961557.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132638627894.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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