题目内容
如图所示,空气中有一块截面为扇形的玻璃砖,折射率为
,现有一细光束,垂直射到
面上,经玻璃砖反射、折射后,经
面平行于入射光束返回,∠
为
,圆半径为
,则入射点
距圆心
的距离为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241336330822809.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633113311.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633207313.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633300316.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633425394.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133632598344.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133632645387.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133632707367.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133632739453.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133632785431.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133632941260.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133632973289.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633019292.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241336330822809.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633113311.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633175532.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633207313.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633253557.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633300316.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633347420.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633378325.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633425394.png)
B
在出射点D处,令出射时的折射角为r,入射角为i,在C点反射角和入射角相等,设为
。由几何关系知r = 45°,则
=
,有i =30°。即有2
+30°= 45°,故
=7.5°,PO = r·sin7.5°。选B
在作球面的反射与折射光线时,要记住入射点的法线过半径的特点,若在其球面内部反射时,则能构成了等腰三角形;若光线从球内以临界角入射时,其出射光线沿入射点的切线。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633456297.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633487542.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133632598344.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633456297.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133633456297.png)
在作球面的反射与折射光线时,要记住入射点的法线过半径的特点,若在其球面内部反射时,则能构成了等腰三角形;若光线从球内以临界角入射时,其出射光线沿入射点的切线。
![](http://thumb2018.1010pic.com/images/loading.gif)
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