如图所示，两束不同的单色细光束a、b，以不同的入射角从空气射入玻璃三棱镜中，其出射光恰好合为一束。以下判断正确的是( )
A．在同种介质中b光的速度较小
B．若让a、b光分别从同种玻璃射向空气，b光发生全反射的临界角较大
C．若让a、b光分别通过同一双缝装置，在同一位置的屏上形成干涉图样，则b光条纹间距较大
D．a、b光中，b的频率大
AD
题目分析：从图象上可知，玻璃对b的折射程度大于a，所以
，即b的频率高，a的频率小，所以D正确。根据
可知，n越大，v越小，所以在同种介质中b光的速度较小，A对。根据
可知，n越大，临界角C越小，所以b光临界角小于a，因此B错。根据干涉公式
可知，b波长短，所以b的间隔小，C错
点评：本题考查了常见的光的传播问题，例如临界角、折射率、干涉条纹等现象。
| 完形填空。 | ||||
| Many people who work in London want to live outside it and to go to their offices, factories or schools every day by train, car or bus, even though this 1 they have to get up earlier in the morning and reach 2 later in the evening. One benefit (好处) of living outside London is that houses are 3 . Even a small flat (公寓) in London without a garden costs quite a lot 4 . With the same money, one can get a little house in the country with a garden of 5 own. Then, in the country one can be 6 from the noise and hurry of the town. 7 one has to get up earlier and spend more time in trains or buses, one can sleep 8 at night, and, during weekends and 9 summer evenings, one can enjoy the 10 air of the country. If one 11 gardens, one can spend one's 12 time digging, planting, watering and doing the hundred and one other jobs which are 13 in the garden. Then, when the flowers and vegetables 14 , one has the reward (回报) of a person who has shared the secrets of 15 . Some people, however, take no interest in country things; for them, 16 lies in the town, with its cinemas and theatres, beautiful shops and busy streets, dance halls and restaurants. Such people would 17 that their life was not worth 18 if they had to live it outside London. A walk in one of the parks and a visit 19 the sea every summer is all the country they 20 . | ||||
|