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
Electromagnetic Energy 1. White light seems to be a combination of all colors. The energy that comes from a source of light
admin
2013-10-25
122
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 kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.
2. The sun is 93 million miles 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(红外线)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 6 ______
选项
答案
E
解析
转载请注明原文地址:https://kaotiyun.com/show/pHmd777K
本试题收录于:
职称英语卫生类B级题库职称英语分类
0
职称英语卫生类B级
职称英语
相关试题推荐
Youwillheartwoconversations.Writedownonewordornumberinthenumberedspacesontheformsbelow.CONVERSATION1(Que
Lookatthequestionsforthispart.Youwillhearapassageabout"ChangesintheRankingsofBritishUniversities".F
Lookatthetenstatementsforthispart.Youwillhearastoryabout"CommunicationThroughTime".Decidewhetheryou
DEALINGWITHWASTEPLASTICEveryyearpeoplethrowawaymillionsoftonnesofplasticbottles,boxesandwrapping.Thesecr
Inthepast,doctorscouldn’tdoanythingaboutstomachulcers.Therehasbeenachangeindoctors’understandingofthecause
Thearticleisaboutacouplewhosemarriedlifeishappierbecause______.Janefinallydecidedtoapplyforherpresentjobb
SomeSundaynewspapersmaybelongtothesamepublishingcompanybutarenoteditedbythesamegroupofpeople.Manyboysand
Coldsarecausedbyexposuretosevereweather.Coldscanbeavoided.
ComputersinCarsYou’refarfromhomeonalonelyroad.Shadowyforestsstretchawayonbothsides.Athickmist(雾)makesit
Babies’ResponseForsometimeinthepastithasbeenwidelyacceptedthatbabies,andothercreatureslearntodothingsb
随机试题
合法有效的行政执法行为具有()。
激光打印机的特点是
心烦神乱,失眠多梦,惊悸怔忡,胸中懊,舌红,脉细数者,治宜选用
A、水提醇沉法B、醇提水沉法C、醇提醚沉法D、铅盐沉淀法E、酸提碱沉法用酸性水从药材中提取出生物碱后再使其从水中析出的方法为
吸收直接投资是指建设项目按照()的原则,直接吸收国家、法人、个人和外商投入资本的一种资本金筹集的重要方式。
个体的自我意识发展经历了从生理自我到社会自我,再到______自我的过程。
2017年1~12月,最接近我国手机出货量接近全年平均数的月份是()。
【S1】【S3】
A、Lossoftheforests.B、LossofitshabitatC、Human’slimitlesshunting.D、Limitedfoodresources.B录音提到,对于现存的熊类而言,最大的威胁是它们栖息地的
Arepasswordspasse(过时的)?It’sstartingtoseemlikeit.Everybodyhatesthem,andnobodycanrememberalltheonesthey’vecrea
最新回复
(
0
)