题目内容
实验室有一块长方体透明介质,截面如图ABCD所示.AB的长度为l1,AD的长度为l2,且AB和AD边透光,而BC和CD边不透光且射到这两个边的光线均被全部吸收.现让一平行光束以入射角θ1射到AB面,经折射后AD面上有光线射出.为了测量该长方体介质的折射率.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250041224143033.jpg)
一同学的做法是:保持射到AB面上光线的入射角θ1不变,用一遮光板由A点沿AB缓慢推进,遮光板前端推到P时,AD面上恰好无光线射出,测得AP的长度为l3,则长方体介质的折射率可表示为n=__________;
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250041224143033.jpg)
一同学的做法是:保持射到AB面上光线的入射角θ1不变,用一遮光板由A点沿AB缓慢推进,遮光板前端推到P时,AD面上恰好无光线射出,测得AP的长度为l3,则长方体介质的折射率可表示为n=__________;
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250041224301268.png)
试题分析:由折射定律可知
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004122446683.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004122461873.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250041224301268.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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