PTE听力口语练习-科学60秒-Focused white light

PTE考生目前最大的问题之一就是练习题缺乏。除了有限的基本官方书(PLUS,Testbuilder, OG)之外就没有题了。很多英语基础不是很扎实的同学很难找到练习材料。悉尼文波雅思PTE培训学校专门为澳洲,尤其是悉尼、墨尔本的PTE考生准备了适合PTE听力阅读练习的科学60秒。各位PTE同学可以练习PTE听力中的summarise spoken text和PTE口语中的retell lecture,PTE听力口语-科学60秒-Frosty Moss练习记笔记技巧和复述。废话少说,下面开始:

This is Scientific American — 60-Second Science. I’m Christopher Intagliata.
LEDs use only a quarter the energy of incandescent bulbs. But despite their efficiency, there isone thing they‘re not that good at: “They have a hard time giving directional light.” SangamChatterjee, a physicist at the University of Marburg and the University of Giessen, in Germany.
Chatterjee and his colleagues may have fixed that. They devised a highly focused, but stillenergyefficient light beam, by starting with something that’s already a highly focusedbeam: a laser. The key is what they shoot the laser at: a substance with a particularstructure. “I‘m always tempted to saywhite powdery substancebut I guess there’s someconnotation on that.”

They synthesized the material from cages of tin and sulfur atoms decorated with hydrocarbonmolecules. The laserproduced infrared lightwhich the human eye cannot seegoes in,but what comes out are many different optical wavelengths. “It’s a molecular light converter. Itbasically changes the color of the light, while retaining the directionality of the lasers. So youcan make something like a white laser beam containing many, many colors.” That mix ofcolors, overall, glows bright white, like a halogen bulb in a beam. The study is in the journalScience.
This sort of lowenergy focused white beam could be used for the very smalllike a lightsource for microscopesto the very big. “You could use this for a spotlight in the theater. Andin the end it should be much more energy efficient than the typical standard spotlight.”Meaning focused white lightthat takes a little heat off the environment.
Thanks for listening Scientific American — 60-Second Science Science. I’m ChristopherIntagliata.


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