题干

如图所示,P、Q是两条平行的、相同的单色光线,入射到半径为R的半圆柱形玻璃砖上表面,玻璃砖下表面AB水平,在AB下方与AB相距h=R的水平光屏MN足够大,己知玻璃砖对P、Q光线的折射率均为 n=2 .光线P沿半径DO方向射入,恰好在圆心O点发生全反射;光线Q从最高点E射入玻璃砖,经折射从下表面AB穿出并打在光屏MN上的F点(图中未画出).求O点与F点的水平距离|O′F|
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答案(点此获取答案解析)

解:光线P恰好在O点发生全反射,设临界角为C.
由折射定律有 sinC=
1
n
,得 C=45°
设光线Q在E点的入射角和折射角分别为θ1和θ2,在AB面上的折射角为θ3,则
θ1

同类题4

阅读下面短文,掌握其大意,然后从1~15各题所给的A、B、C和D项中,选出最佳选项。

People often say that you can not change the environment, but can change yourself; you can not change the past, but now can be changed; you can not change the facts, but can change attitudes.

Indeed, one key to the success lies in his 1. The difference between successful people and the losers are: 2attribute setbacks and difficulties to personal ability, experience, imperfect, to 3the internal(内在的), they are willing to continuously improve and develop the right direction; while the losers will blame on the opportunity, and the environment injustice, emphasizing external(外在的) and4factors that created the position of their life, they always5, wait and give up!

Person’s appearance or his family is a priori (先验的)condition that can not be changed, but at least the inner state, the spirit of the will is 6 in their control. Mentality determines the final height of life. There is no absolute bad thing, only the absolute7mentality. If a person even cannot 8the state of mind, how can he deal with things more complicated than the mentality?

No matter what the situation is, a person’s 9 is very important. That you put10or numbness in your work makes completely different. Emerson said:When one keeps moving toward his goal,the whole world will stand away from his way.On the contrary, failure is not because we do not have the11, but because we are susceptible(易受影响的) to all around us with an unstable attitude, and are easily12

As long as we believe the power of mind, change our attitude and have the13to face the disappointments in life, do not despair, we can14succeed. Believe the power of mind because 15determines the final height of life.