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
Electromagnetic Energy 1 White light seems to be a combination of all colors. The energy that comes from a source of light i
Electromagnetic Energy 1 White light seems to be a combination of all colors. The energy that comes from a source of light i
admin
2013-11-20
36
问题
Electromagnetic Energy
1 White light seems to be a combination of all colors. The energy that comes from a source of light is not limited to the kind of energy you can see. Heat is given off by a flame or an electric light. On a cloudy day it is possible to get a sunburn even though you feel cool. Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.
2 The sun is 93 million miles away from the earth. Yet we can use energy from the sun because electromagnetic energy travels through space.
3 Many other kinds of energy are also types of electromagnetic energy. Radio, television, and radar signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared(红外线的)radiation is an electromagnetic wave. When it is absorbed by matter, heat is produced. Waves of infrared and visible light have more energy than waves of radio, television, or radar. Ultraviolet rays(紫外线)and X-rays are electromagnetic waves with even greater amounts of energy. Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms. X-rays and gamma rays have so much energy that they travel right through solid objects. They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal, and in medicine to reveal broken bones.
4 Usually we use electricity to generate electromagnetic energy. The source of most of our energy is the sun. Heat from the sun causes water to evaporate. When the water falls to the earth as rain, some of it is trapped behind dams and then used to operate electric generators. Other generators are powered by coal, but the energy stored in coal came from the sun, too.
5 Until recently, the source of the tremendous amount of energy given off by the sun was a puzzle. If the sun depended on chemical reactions, it would have used up all its energy long ago. Experiments with electromagnetic radiation led to the theory that mass can be converted into energy. About forty years after the theory was proposed, nuclear energy was harnessed(利用)by man. Chemical energy comes from electron(电子)rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemical reactions, nuclear reactions release millions of times more energy per pound of fuel. We now believe that the sun’ s energy comes from the nuclear reactions in which hydrogen is changed into helium(氦).
6 Nuclear energy is beginning to compete with coal as an economical source of power to generate electricity. It is also being used to operate engines in large ships. Scientists continue to seek new and better methods of obtaining and using energy.
A. Nuclear Reactions as the Lasting Source of the Sun’ s Energy
B. The Most Important Source of Energy
C. Types of Electromagnetic Energy
D. X-rays Are Used to Detect and Treat Cancer
E. Seeking New Sources of Energy
F. Nuclear Energy Is Beginning to Compete With Coal
Paragraph 5______
选项
答案
A
解析
第五段的最后一句为主题句,意为:我们现在相信太阳的能量来自核反应,在此过程中,氢转变为氦。A项“Nuclear Reactions as the Lasting Source of the Sun’s Energy(核反应是太阳能最持久的来源)”与主题句意思吻合,故选A。
转载请注明原文地址:https://kaotiyun.com/show/RZQd777K
本试题收录于:
职称英语理工类B级题库职称英语分类
0
职称英语理工类B级
职称英语
相关试题推荐
ABiologicalClockEverylivingthinghaswhatscientistscallabiologicalclockthatcontrolsbehavior.Thebiologicalclo
TheStoryofLaniFive-year-oldLanistilltakessevenmedicineswithherbreakfasteverymorning."She’sverygoodaboutit
TeachingandLearningMedicineAwardTwoscientistswhohavewonpraiseforresearchintothegrowthofcancercellscouldb
ExercisingYourMemory1Agingdoesnotmeanadramaticdeclineinmemorypower,unlessyouhelpithappenbylettingyourmind
ScientistsDevelopWaysofDetectingHeartAttackGermanresearchershavecomeupwithanewgenerationofdefibrillators(除颤
Ticketsarelimitedandwillbeallocatedtothosewhoapplyfirst.
2.Theeternalmotionofthestarsfascinatedhim.
Thepolicewillneedtokeepawaryeyeonthisareaoftown.
Sheseemedtohavedetectedsomeangerinhisvoice.
Thereseemedtobenomotiveforthemurder.
随机试题
按信令传送信道和用户消息传送信道的关系,可分为随路信令和___________信令。
某企业截至评估基准日应收账款余额为360万元,前5年应收账款余额合计为1470万元,处理坏账合计58.8万元,该企业应收账款评估值为【】
A、 B、 C、 D、 C
下列血浆脂蛋白中胆固醇含量最高、最低的分别是
下列哪项不是急性肾小球肾炎的特点
根据《建筑内部装修防火施工及验收规范》规定,木质材料表面进行防火涂料处理时,涂刷防火涂料用量不应少于()。
Thepairwords"lift"and"elevator"are
对于入园初期适应困难的孩子,幼儿园教师可以()。
下列叙述中正确的是( )。
A、Shehadaminoraccident.B、Shecaughtaseriouscold.C、Shecaredtoomuchaboutherlooking.D、Shegotstuckinthetraffic.
最新回复
(
0
)