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    The Bazaar of Bad Dreams

    Author: Stephen King

    US author Stephen King is well-known for creating contemporary horror, supernatural fiction and science fiction stories. His latest book delivers a generous collection of stories with hidden connections. The master storyteller also includes insight into why and how he came to write them.

    Magnus Chase and the Gods of Asgard

    Author: Rick Riordan

    A troubled kid named Magnus Chase has lived alone on the streets of Boston since his mother's mysterious death. His life changes when he meets Uncle Randolph, a man his mother warned him about. Randolph reveals that Chase is the son of a Norse god. Chase is then tasked with searching for a lost weapon to save the world from monsters.

    Little Victories: Perfect Rules for Imperfect Living

    Author: Jason Gay

    There are always moments in our lives when we feel doomed(注定) to be imperfect. In this collection of humorous essays,Wall Street Journal columnist Jason Gay tells us that, when we mess things up,we should just give ourselves a break and celebrate the things we did right.

    Thing Explainer: Complicated Stuff in Simple Words

    Author: Randall Munroe

    Have you ever been puzzled by complex terminology (术语)? Has it prevented you from learning about science? This fascinating book provides simple explanations and line drawings to explain essential science concepts. The book's author is the man behind the popular science blog -- What If.

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阅读《光的全反射》,回答:

光的全反射

    如图1所示,当光线从玻璃斜射入空气里的时候,一部分光会进入空气里发生折射,此时折射角β大于入射角α.若入射角增大时,折射角也随之增大,当入射角增大到某值时(小于90°),折射角会增大到90°.若继续增大入射角,此时空气中没有折射光射出,光线全部反射回玻璃,这种现象叫做光的全反射.折射角等于90°时的入射角称为临界角.当光从水或玻璃射入空气时,只要入射角大于临界角,光就会发生全反射.

海面上出现的海市蜃楼奇景如图2所示,就是因为光的在空气层中多次折射和全反射而形成的自然景观.在夏季,白昼海水温度比较低,所以在海面上方的空气出现下冷上暖的现象.由于空气的热胀冷缩,因此空气层下密上疏.景物的光线先由密的空气层逐渐折射进入稀的空气层,并在上层发生了全反射,光线又折回到下层密的气层中来,经过这样弯曲的线路,最后投入人的眼中.由于人的视觉总是感到物像是来自直线方向的,因此看到的“景物”比实物抬高了许多.

人们利用光的全反射的现象制成了光缆,用于通信等方面.光在均匀透明的玻璃棒中传播,即可在弯曲的玻璃棒的光滑内壁上,借助于接连不断地全反射,可以将光从一端传导到另一端,即使棒的截面直径很小,甚至到微米数量级,传导的效果也不变,这种导光的细玻璃丝称为光导纤维如图3所示.

    光导纤维束已成为一种新的光学基本元件,在光通信、光学窥视及光学特殊照明等方面有重要的应用.荣获2009年诺贝尔物理学奖的华裔科学家高锟在此方面贡献突出,被世界誉为“光纤通讯之父”.

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