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
Learn about Light 1. Ancient civilizations were amazed by the existence of light for thousands of years. The Greek philosophe
Learn about Light 1. Ancient civilizations were amazed by the existence of light for thousands of years. The Greek philosophe
admin
2012-12-06
71
问题
Learn about Light
1. Ancient civilizations were amazed by the existence of light for thousands of years. The Greek philosophers believed that light was made up of countless, tiny particles that enter the human eye and create what we call vision. However, Empedocles and a Dutch scientist named Christian Huygens believed that light was like a wave. According to them, light spread out and travelled like a straight line. This theory was accepted during the 19th century.
2. ln 1905, Albert Einstein published a research paper in which he explained what is referred to as the photoelectric effect. This theory explains that particles make up light. The particles Einstein was referring to are weightless bundles(束)of electromagnetic(电磁)energy called photons(光子). Today, scientists agree that light has a dual(二重) nature — it is part particle and part wave. It is a form of energy that allows us to see things around us.
3. Things that give off light are known as sources of light. During the day, the primary source of light is the sun. Other sources of light include stars, flames, flashlights, street lamps and glowing gases in glass tube.
4. When we draw the way light travels we always use straight lines. This is because normally light rays travel in a straight line. However, there are some instances that can change the path and even the nature of light. They are reflection, absorption, interference (干扰), etc.
5. Physicists have attempted to measure the speed of light since the early times. In 1849, Hippolyte Fizeau conducted an experiment by directing a beam of light to a mirror located kilometers away and placed a rotating cogwheel(旋转齿轮)between the beam and the mirror. From the rate of rotation of the wheel, number of wheel’s teeth and distance of the mirror, he was able to calculate that the speed of light is 313 million meters per second. In a vacuum(真空),however, the speed of light is 299,792,458 meters per second. This is about a million times faster than the speed of an airplane.
A. How is the nature of light explained today?
B. What are sources of light?
C. How did physicists measure the speed of light?
D. How does light travel?
E. How did people think of light years ago?
F. What causes a shadow?
Paragraph 2 ______.
选项
答案
A
解析
转载请注明原文地址:https://kaotiyun.com/show/SLQd777K
本试题收录于:
职称英语理工类C级题库职称英语分类
0
职称英语理工类C级
职称英语
相关试题推荐
MenTooMaySufferFromDomesticViolenceNearlythreein10menhaveexperiencedviolenceatthehandsofanintimatepartn
MenTooMaySufferFromDomesticViolenceNearlythreein10menhaveexperiencedviolenceatthehandsofanintimatepartn
MenTooMaySufferFromDomesticViolenceNearlythreein10menhaveexperiencedviolenceatthehandsofanintimatepartn
ProlongingHumanLifeProlonginghumanlifehasincreasedthesizeofthehumanpopulation.Manypeoplealivetodaywouldha
Itisobviousthatithasbeentoolatetotakeaction.
Recentpressureatworkmayaccountforhisbehavior.
Recentpressureatworkmayaccountforhisbehavior.
Idon’tfeelsecurewhenIamaloneinthehouse.
ArtificialSpeechBecausespeechisthemostconvenientformofcommunication,inthefuturewewantessentiallynaturalcon
随机试题
下述疾病有脾切除适应证的有
化学发光酶免疫测定中常用的发光底物为
下列哪种培养基属于肠杆菌科的强选择培养基
路面面层应具有( )、耐磨、抗滑。
某大型工程,由于技术特别复杂,对施工单位的施工设备及同类工程的施工经验要求较高,经省有关部门批准后决定采取邀请招标方式。招标人于2009年3月8日向通过资格预审的A、B、C、D、E五家施工承包企业发出了投标邀请书,五家企业接受了邀请并于规定时间内购买了招标
根据年龄层可以把生涯规划比照家庭生命周期分为6个阶段,理财活动侧重于偿还房贷、筹集教育金的是()。
Backintheolddays,whenIwasachild,wesataroundthefamilyroundtableatdinnertimeandexchangedourdailyexperiences
在韵律活动中使用道具,应遵循的原则是()。
修筑高速公路经过某村,需搬迁一批农户。为了节约土地资源和保护环境,政府统一规划搬迁建房区域。若搬迁农户建房每户占地150平方米,则绿色环境占地面积占总面积的40%;政府又鼓励其他有积蓄的农户到规划区建房,这样又有20户农户加入建房,若仍以每户占地150平方
甲、乙两人在同一时间就同样的发明创造提交了专利申请,专利局将分别向各申请人通报有关情况,并提出多种解决这一问题的办法,不可能采用(19)的办法。
最新回复
(
0
)