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
28
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.
Paragraph 5______
选项
A How does light travel?
B How did people think of light years ago?
C How is the nature of light explained today?
D How did physicists measure the speed of light?
E What causes a shadow?
F What are sources of light?
答案
D
解析
本段第一句是主题句。它说明了该段的主题思想:自古以来,物理学家们一直试图 测量光速。然后列举出测量光速的例子。
转载请注明原文地址:https://ti.zuoweng.com/ti/Y79QKKKQ
相关试题推荐
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...
第三篇TheWorld’sBest-SellingMedicine Sinceancienttimes,peopleallover...
第三篇TheWorld’sBest-SellingMedicine Sinceancienttimes,peopleallover...
第三篇TheWorld’sBest-SellingMedicine Sinceancienttimes,peopleallover...
弟一篇TheWorkfsBest-Se川ngMedicine Sinceancienttimes,peoplealloverthe...
共用题干 第三篇TheWorld'sBest-SellingMedicineSinceancienttimes,peopleallov...
随机试题
菲利普斯和伯奎斯特的客户个性偏好分析模型中的4种客户类型是( )。 A、现实
进行中等运动强度耐力训练时,表明运动强度合适的项目是 A.呼吸不变,心率加快
诊断类风湿关节炎,X线检查最有价值的部位是 A、双侧肘关节 B、双侧肩关节
项目可行性研究应具有()。[2004年真题]
根据《建设工程施工劳务分包合同(示范文本)》(GF-2003-2014),应由劳
以治法分类方剂的代表著作是
关于儿童青少年每天身体活动描述正确的是()A.大多数日常身体活动应该是有氧活动B.每天累计至少60分钟中等或低强度身体活动C.每天累计至少60分钟中等到高强
胰岛素治疗的指征包括A.1型糖尿病B.肥胖2型糖尿病患者C.糖尿病酮症酸中毒、高渗性昏迷、乳酸酸中毒伴高血糖时D.合并重症感染、消耗性疾病、严重视网膜、
木瓜的道地产区是A:广东B:广西C:安徽D:新疆E:辽宁
有关静脉注射脂肪乳剂的正确表述有A.要求80%微粒的直径B.是一种常用的血浆代用品C.可以使用聚山梨酯80作为乳化剂D.可以使用普朗尼克F68作为乳