2. 外语
  3. LED Lighting 1 An accidental discovery announced recently has taken LED lighting to a new level, suggesting it could soon o

LED Lighting 1 An accidental discovery announced recently has taken LED lighting to a new level, suggesting it could soon o

admin2011-01-02  61
问题                             LED Lighting
    1  An accidental discovery announced recently has taken LED lighting to a new level, suggesting it could soon offer a cheaper, longer-lasting alternative to the traditional light bulb. The breakthrough adds to a growing trend that is likely to eventually make Thomas Edison’s bright invention obsolete. LEDs are already used in traffic lights, flashlights, and architectural lighting. They are flexible and operate less expensively than traditional lighting.
    2  Michael Bowers, a graduate student at Vanderbilt University, was just trying to make really small quantum dots, which are crystals generally only a few nanometers big. Quantum dots contain any where from 100 to 1,000 electrons. They’re easily excited bundles of energy, and the smaller they are, the more excited they get. Each dot in Bower’s particular batch was exceptionally small, containing only 33 or 34 pairs of atoms.
    3  When you shine a light on quantum dots or apply electricity to them, they react by producing their own light, normally a bright, vibrant color. But when Bowers shined a laser on his batch of dots, something unexpected happened. He was surprised when a white glow covered the table. The quantum dots were supposed to emit blue light, but instead they were giving off a beautiful white glow.
    4  Then Bowers and another student got the idea to stir the dots into polyurethane and coat a blue LED light bulb with the mix. The lumpy bulb wasn’t pretty, but it produced white light similar to a regular light bulb.
    5  LEDs produce twice as much light as a regular 60 watt bulb and burn for over 50,000 hours. The Department of Energy estimates LED lighting could reduce U.S. energy consumption for lighting by 29 percent by 2025. LEDs don’t emit heat, so they’re also more energy efficient. And they’re much harder to break.
    6  Quantum dot mixtures could be painted on just about anything and electrically excited to produce a rainbow of colors, including white. The main light source of the future will almost surely not be a bulb. It might be a table, a wall, or even a fork.     
    A. LED Lighting Is Not Mature
    B. LED Lighting Will Replace Traditional Lighting
    C. Almost Everything Could Be the Main Light Source in the Future
    D. LED Lighting Has Many Advantages
    E. Bowers Made an Unexpected Discovery
    F. LED Light Bulbs Look Lumpy
Paragraph 3 ______.
选项
答案E
解析 Bowers做实验目的并非寻找新照明源。量子点在激光的激发下发出白光是一次意外的发现。段中用了“unexpected”和“surprised”都说明了这一点。第一段的“accidental discovery”也佐证了这是一次偶然的发现。因此，E是正确答案。
转载请注明原文地址:https://kaotiyun.com/show/kjLd777K
本试题收录于： 职称英语理工类A级题库职称英语分类
0

职称英语理工类A级

职称英语

相关试题推荐
随机试题
最新回复(0)