首页
财务会计
医药卫生
金融经济
考公考编
外语考试
学历提升
职称考试
建筑工程
IT考试
其他
登录
职称考试
Learn about Light 1 Ancient civilizations were amazed by the existence of li...
Learn about Light 1 Ancient civilizations were amazed by the existence of li...
admin
2020-12-24
39
问题
Learn about Light
1 Ancient civilizations were amazed by the existence of light for thousands of years. The Greek philosophers believed thatlight 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 In 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.
Stars, flames, flashlights are some examples of ______
选项
A a straight line
B a beam of light
C sources of light
D the path of light
E a form of energy
F the speed of light
答案
C
解析
根据第三段最后一句。
转载请注明原文地址:https://ti.zuoweng.com/ti/i79QKKKQ
相关试题推荐
Theydidn’tseemtoappreciatethemagnitudeoftheproblem.A.existenceB.caus
共用题干 OlderVolcanicEruptionsVolcanoesweremoredestructiveinancienthist...
共用题干 OlderVolcanicEruptionsVolcanoesweremoredestructiveinancienthist...
共用题干 OlderVolcanicEruptionsVolcanoesweremoredestructiveinancienthist...
共用题干 OlderVolcanicEruptionsVolcanoesweremoredestructiveinancienthist...
Thiscityisfamousforitsmagnificentancientbuildings.A:contemporary B:dist
第三篇TheWorld’sBest-SellingMedicine Sinceancienttimes,peopleallover...
弟一篇TheWorkfsBest-Se川ngMedicine Sinceancienttimes,peoplealloverthe...
弟一篇TheWorkfsBest-Se川ngMedicine Sinceancienttimes,peoplealloverthe...
共用题干 第三篇TheWorld'sBest-SellingMedicineSinceancienttimes,peopleallov...
随机试题
某公司生产单一产品,实行标准成本管理。每件产品的标准工时为3小时,固定制造费用的
康复医学确立于 A.古代的中国、希腊、罗马时代 B.第一次世界大战前后 C
面对一张张充满期待的面孔,新来的班主任说:“新学年到来了,你们的人生也翻开了新的
行政强制的设定和实施应当遵循法定性、适当性、教育与强制相结合、禁止谋取私利等原则
下列关于资产负债表的编制,说法正确的有()。
二级公路机电工程分项资质承包的工程范围包括()。A.一级以下公路通信、监控、收费机电系统及配套工程系统的施工及安装B.一级以下公路干线传输系统等机电系统及配
公路隧道主要开挖方法是()A、明挖法B、钻爆法C、盾构法D、盖挖法
社会工作者通过绘制社区地图、印发宣传单等方式,为居民提供现有的社会服务资料,告知居民社区资源的分布。此外,还会通过一些小组课程,教授居民运用社会资源来改善...
共用题干 某家电生产企业每月对某种金属的需求量是10吨,单价为300元/吨,每次订货的订购费用为700元,每吨该种金属的保管费用为12%。根据以上资料,...
企业随同产品出售单独计价的包装物成本应计入销售费用。()