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
Volts from the Sky 1.Lightning has caused awe and wonder since old times. Although Benjamin Franklin demonstrated lightning a
Volts from the Sky 1.Lightning has caused awe and wonder since old times. Although Benjamin Franklin demonstrated lightning a
admin
2010-01-13
48
问题
Volts from the Sky
1.Lightning has caused awe and wonder since old times. Although Benjamin Franklin demonstrated lightning as an enormous electrical discharge more than 200 years ago, many puzzles still surround this powerful phenomenon.
2.Lightning is generated when electrical charges separate in rain clouds, though processes are still not fully understood. Typically, positive charges build at the cloud top, while the bottom becomes negatively charged. In most instances of cloud-to-ground lightning, the negatively charged lower portion of the cloud repels negatively charged particles on the ground’s surfaces, making it become positively charged, The positive charge on the ground gathers at elevated points.
3.A flow of electrons begins between the cloud and earth. When the voltage charge becomes large enough, it breaks through the insulating barrier of air, and electrons zigzag earthward. We see the discharge as lightning.
4.Lightning can occur within a cloud, between clouds, or between clouds and the ground. The first variety, intra-cloud lightning, is the most frequent but is often hidden from our view. Cloud-to -ground lightning, making up about 20 percent of lightning discharges, is what we usually see lightning comes in several forms, including sheet, ribbon, and ball, Intra-cloud lightning can illuminate a cloud so it looks like a White sheet, hence its name. When cloud-to-ground lightning occurs during strong winds, they can shift the lightning channel sideways, so it looks like a ribbon. The average lightning strike is more than 3 miles long and can travel at a tenth of the speed of light. Ball lightning, the rarest and most mysterious form, derives its name from the small luminous ball that appears near the impact point, moves horizontally, and lasts for several seconds.
5.Thunder is generated by the tremendous heat released in a lightning discharge second. This sudden heating acts as an explosion, generating shock waves we hear as thunder.
6.About 2,000 thunderstorms are occurring in the world at any time, generating about 100 lightning strikes every second, or 8 million daily. Within the United States, lightning strikes are estimated at 20 million a year, or about 22,000 per day. You have a 1-in-600,000 chance of being struck by lightning during your lifetime. Lightning can strike twice or more in the same spot. The Empire State Building in New York is struck by lightning about two dozen times annually.
7.You can measure how far you are from a lightning strike by counting the seconds between viewing the flash and hearing the bang, and then dividing by five. This approximates the mileage.
A.Cloud-to-ground lightning occurring in the U. S.
B.Types of lightning
C.Cause of lightning
D.Differences between thunder and thunderstorm
E.Frequencies of thunderstorms occurring in the world and the U. S
F.Shock waves as thunder
选项
答案
C
解析
第二段以云层到地面的闪电为例子解释了闪电的原理。第三段述及闪电发生的过程。
转载请注明原文地址:https://kaotiyun.com/show/UNGd777K
本试题收录于:
职称英语综合类基础题库职称英语分类
0
职称英语综合类基础
职称英语
相关试题推荐
SaveEnergyAtHomeOntheaverage,Americanswasteasmuchenergyastwo-thirdsoftheworld’spopulationconsumes.That’slar
CropProblemAdvancesintechnologyhavehelpedmoreoftheworld’spopulationlivebetterandlonger,andthatispartofo
Pesticides(杀虫剂)Whydopesticides(杀虫剂)fitintothepictureofenvironmentaldisease?Wehaveseenthattheynowpollutesoi
UnpopularSubjects?Isthereaplaceintoday’ssocietyforthestudyofuselesssubjectsinouruniversities?Justover100
PuertoRicanCuisine(菜肴)PuertoRico,aCaribbean(加勒比海区)islandrichinhistoryandremarkablenaturalbeauty,hasacuisine
TheweatherisaconstantsubjectofconversationinBritain.
ListeningDeviceProvidesLandslide(山崩;地滑;塌方)EarlyWarningAdevicethatprovidesearlywarningofalandslidebymonitoring
FewFactsaboutSingapore1.SingaporeisanindependentcitystateinsoutheasternAsia,consistingofonemajorisland—the
Whatarethetwodeclarationsconcernedwith?Thephrase“kickedaround”(paragraph4)couldbebestreplacedby
随机试题
设exsin2x为某n阶常系数线性齐次微分方程的一个解,则该方程的阶数n至少是___________,该方程为___________.
ThebusislateandJulieiscold.She______forthebusfor10minutes.
A.蛋白质紫外吸收的最大波长280nmB.蛋白质是两性电解质C.蛋白质分子大小不同D.蛋白质溶液为亲水胶体盐析分离蛋白质的依据是
A.医生检查患者时,由于消毒观念不强,造成交叉感染B.医生满足患者的一切保密要求C.妊娠危及母亲的生命时,医生给予引产D.医生对患者的呼叫或提问给予应答E.医生的行为使某个患者受益,但却损害了别的患者的利益上述各项中属于医生违背不伤害原则的是
A、附子配干姜B、丁香配柿蒂C、吴茱萸配干姜D、附子配麻黄、细辛E、高良姜配香附治虚寒呕呃宜选用
郭某应聘到天天饭店做厨师,双方于2008年1月签订了劳动合同。合同中约定试用期为1年,试用期间包食宿,不支付了资,不为郭某缴纳社会保险费用,试用期满进行考试,若考试不合格则不予录用,合格则录用为正式员工,每月工资2000元。天天饭店称由于是餐饮行业,为食品
入伙的新合伙人与原合伙人可以在入伙协议中约定,新合伙人比原合伙人享有较大的权利,承担较小的责任。()
在Python中,包含矩阵运算的第三方库是()。
在考生文件夹下,打开文档WORDl.docx,按照要求完成下列操作并以该文件名(WORD1.docx)保存文档。【文档开始】高速CMOS的静态功耗在理想情况下,CMOS电路在非开关状态时没有直流电流从电源Vcc到地,因而器件没有静态功耗。对所有的C:M
A、寄信B、别迟到C、要仔细D、写总结B
最新回复
(
0
)