首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
to get from Kathmandu to the tiny village in Nepal, Dave Irvine-Halliday spent more than two days. When he arrived, he found vil
to get from Kathmandu to the tiny village in Nepal, Dave Irvine-Halliday spent more than two days. When he arrived, he found vil
admin
2013-01-12
49
问题
to get from Kathmandu to the tiny village in Nepal, Dave Irvine-Halliday spent more than two days. When he arrived, he found villagers working and reading around battery-powered lamps equipped with light-emitting diodes, or LEDs--the same lamps he had left there in 2000.
Irvine-Halliday, an American photonics engineer, was not surprised. He chose to use LED bulbs because they are rugged, portable, long-lived, and extremely efficient. Each of his lamps produces a useful amount of illumination from just one watt of power. Villagers use them about four hours each night, then top off the battery by pedaling a generator for half an hour. The cool, steady beam is a huge improvement over lamps still common in developing Countries. In fact, LEDs have big advantages over familiar incandescent (白炽的)lights as well--so much so that Irvine-Halliday expects LEDs will eventually take over from Thomas Edison’s old lightbulb as the world’s main source of artificial illumination.
The dawn of LEDs began about 40 years ago, but early LEDs produced red or green glows suitable mainly for displays in digital clocks and calculators. A decade ago, engineers invented a semiconductor crystal made of an aluminum compound that produced a much brighter red light. Around the same time, a Japanese engineer developed the first practical blue LED. This small advance had a huge impact because blue, green, and red LEDs can be combined to create most of the colors of the rainbow, just as that in a color television picture.
These days, high-intensity color LEDs are showing up everywhere such as the traffic lights. The reasons for the rapid switchover are simple. Incandescent bulbs have to be replaced annually, but LED traffic lights should last five to yen years. LEDs also use 80 to 90 percent less electricity than the conventional signals they replace. Collectively, the new traffic lights save at least 400 million kilowatt-hours a year in the United States.
Much bigger savings await if LEDs can supplant Mr. Edison’s bulb at the office and in the living room. Creating a white-light LED that is energy-saving, cheap and appealing has proved a tough engineering challenge. But all the major lightbulb makers--including General Electric, Philips, and Osram-Sylvania -- are teaming up with semiconductor manufacturers to make it happen.
Which of the following statements does not agree with the facts in the passage?
选项
A、The displays in digital clocks and calculators are just produced by early LEDs.
B、Irvine-Halliday believes that LED will certainly become the world’s main source of artificial light.
C、A decade ago, engineers developed red and blue LEDs, which were regarded as a mile-stone in this research.
D、It is the blue LED developed by a Japanese engineer that had a great impact on the research process.
答案
C
解析
这是一道事实寻读题。第3段说,10年前一位日本工程师研制出了蓝色发光二极管,这个小小的进展具有极大的影响,因为红、绿、蓝是组成彩虹的主要颜色。
转载请注明原文地址:https://kaotiyun.com/show/DO9O777K
0
考博英语
相关试题推荐
______ifIhadarrivedyesterdaywithoutlettingyouknowbeforehand?
Afterwalkingforhourswithoutfindingthevillage,webegantohave_______aboutourmap.
Myauntlosthercatlastsummer,butit____aweeklateratahomeinthenextvillage.
Thepeopleofthevillagefoughtfortherightto________cattleonthegrassland.
随机试题
正畸治疗后牙槽骨由过度性骨到正常
A.叶酸B.次黄嘌呤C.谷氨酰胺D.胸腺嘧啶E.天冬酰胺氮杂丝氨酸的化学结构类似于
合同履行的原则有()。
编制会计报表是企业账务处理程序的组成部分。()
关于另类投资,以下表述正确的是()。
商业银行的贷款平均额和核心存款平均额间的差构成了()。
我国的四大道教名山是指()。
生态足迹也称生态占用,是指特定数量人群按照某一种生活方式所消费的、自然生态系统提供的各种商品和服务功能,以及在这一过程中所产生的废弃物需要环境(生态系统)吸纳,并以生物生产性土地(或水域)面积来表示的一种可操作的定量方法。通过生态足迹将需求与自然生态系统的
竹:高洁:品质
Thismaterial______well.
最新回复
(
0
)