2015年職稱英語考試理工類A級強化模擬試題4
發布時間：2015-02-07 共1頁
LED Lighting
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 invention1 obsolete. LEDs are already used in traffic lights, flashlights, and architectural lighting. They are flexible and operate less expensively than traditional lighting.
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 anywhere 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.
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 light4, but instead they were giving off a beautiful white glow.
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.
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.
Quantum dot mixtures could be painted on just about anything and electrically excited to produce a rainbow of colors t 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.
23. Paragraph 1_____
24. Paragraph 3_____
25. Paragraph 5_____
26. Paragraph 6_____
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
27. Unlike traditional lighting, LEDs do not give out heat so_____.
28. Edison’s bright invention is likely to be outdated because_____.
29. Something unexpected happened during Bower’s experiment when_____.
30. Over one quarter of energy consumption for lighting could be saved by 2025 if .
A. traditional lighting is less durable and dearer
B. a laser excited the quantum dots
C. America adopted LEDs
D. graduate students work hard
E. quantum dot mixtures are magic
F. it is more efficient
參考答案：23-30BED CFABC
