题目内容
如左图所示,空间存在着竖直向下的B=0.5T的匀强磁场,MN、PQ是放在同一水平面的光滑平行长直导轨,其间距L=0.2m,R是连接在导轨一端的电阻,ab是跨接在导轨上的导体棒,从零时刻开始,对a b加以大小为F=0.45N,方向水平向左的水平拉力,使其从静止开始沿导轨运动,此过程中,棒一直保持与导轨垂直且良好接触,右图是导体棒的速度时间图象,其中AO是图象在O点的切线,AB是图象的渐近线。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412391726919791.png)
(1)除R以外,其余部分电阻均不计,求R的阻值。
(2)当ab位移100m时,其速度刚好到达10m/s,求此过程中电阻R上产生的热量
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412391726919791.png)
(1)除R以外,其余部分电阻均不计,求R的阻值。
(2)当ab位移100m时,其速度刚好到达10m/s,求此过程中电阻R上产生的热量
⑴0.22Ω (10分)
⑵36J
⑵36J
本题考查的是法拉第应电磁感定律,以及用能量的观点解决问题
步骤:
根据法拉第应电磁感定律,E=BLV…
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917347720.png)
…![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917379400.png)
三式联立
,代入数据R=0.22![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917425333.png)
因为OA是渐近线,根据牛顿第二定律
,
,由功能关系
,
代入数据![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917628544.png)
步骤:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917285369.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917285369.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917347720.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917363710.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917379400.png)
三式联立
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917410729.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917425333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917472431.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241239175031205.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241239175351007.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917581881.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917597885.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123917628544.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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