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
The electromagnet was invented in England by William Sturgeon, who took an iron rod and bent it into the shape of a horseshoe. T
The electromagnet was invented in England by William Sturgeon, who took an iron rod and bent it into the shape of a horseshoe. T
admin
2012-07-17
65
问题
The electromagnet was invented in England by William Sturgeon, who took an iron rod and bent it into the shape of a horseshoe. This "horseshoe" was coated with varnish (清漆) and a layer of copper wire was wrapped around it. An electric current was passed through the wire, thus making the rod magnetic. The rod was now, because of magnetic attraction, able to support nine pound of iron.
In the US, a scientist named Joseph Henry improved on Sturgeon’s electromagnet by insulating (使绝缘) the copper wire with silk. He was able to wrap many turns of wire around an iron core without danger of circuits between the turns. His magnet could hold 2 300 pounds.
This experiment prompted Henry to try his hand at converting magnetism into electricity. First he coiled (缠绕, 盘绕) some insulated wire around an iron bar, connecting both ends of the wire to a galvanometer (电流计). The iron bar was placed across the poles of the electromagnet. Then the coil of the electromagnet was connected to a battery. The galvanometer indicated a voltage , then dropped to zero. Henry signaled his assistant to disconnect the coil. The galvanometer showed that once again a voltage had been produced, although this time in the opposite direction. The principle of electromagnet induction (感应现象) had thus been discovered. Unfortunately for Joseph Henry he did not publish findings and someone else (Faraday) got the credit for the discovery.
The galvanometer indicated______.
选项
A、that Henry’s assistant had connected the wire
B、that Henry had been able to produce a voltage
C、zero constantly
D、the iron bar had been placed across the poles of the electromagnet
答案
B
解析
本题是一道具体细节题。问电流计指示了什么。利用查阅式阅读法,文章第三段后半部分指出,亨利着手搞起了磁、电转换实验。他先将一些绝缘导线绕在一根铁条上,并将导线的两端与一个电流计连接起来。这根铁条被放在电磁铁的两个极上,然后将电磁铁的线圈接通电源。这时,电流计指示出一个电压,然后,指针又回到了零。亨利示意他的助手将线圈断开连接,此时,电流计上又一次指示出一个电压,但这次的电压是反向的。因此,本题的正确答案应是B“电流计指示线路中产生了电压”。
转载请注明原文地址:https://kaotiyun.com/show/49XO777K
0
在职攻硕英语联考
相关试题推荐
Theamazingsuccessofhumansasa【C1】______istheresultoftheevolutionarydevelopmentofourbrainswhichhasled,amongoth
InatotalofsixstatesinthemiddleofAmerica,15,000assembly-lineworkersare【C1】______Japanesecarstogether.Theseautow
Ifyouwantto______apleasantvisit,findoutasmuchaspossibleaboutthemannersandcustomsofyourhostcountry.
Somepeoplebelievethat"KingJohn"waswrittenbyShakespeare,butsomepeoplethinkitmightbewrittenbyan______author.
Cultureisactivityofthought,andreceptivenesstobeautyandhumanefeeling.【C1】______ofinformationhavenothingtodowith
Microfinanceisananti-povertytool.Ifyoumakesmallloanstogroupsofpoorwomen,theyalwaysrepaythemontime.Microfina
Gender-basedviolencebothreflectsandreinforcesinequitiesbetweenmenandwomenand______thehealth,dignity,securityand
ThemanwhoinventedCoca-ColawasnotanativeAtlantan,butonthedayofhisfuneraleverydrugstoreintowntestimoniallysh
IthinkIwasatschool,IwasstayingwithafriendduringthevacationwhenIheardthenews.
随机试题
IEEE802.3的物理层协议10BASE-T规定从网卡到集线器的最大距离为____。
1981年9月30日,叶剑英发表了【】
遗忘是识记过的内容不能再认与回忆。信息加工观点认为,遗忘是信息提取不出来。
根据我国海关的相关规定,对于外商提供的金额不超过5000美元的辅料,可以凭合同办理“进出口货物征免税证明”,且不需要核销。()
张三为加入东方合伙企业需要一笔资金,于2015年2月2日向建行借款10万元,双方以书面合同约定;借款期限为2年;借款年利率为6%,2年应付利息由建行预先在借款本金中一次扣除;借款期满时张三一次偿还全部借款。李四为张三的保证人,与建行签订保证合同,约定李四承
在结案期,当发现没有可能阻止结案时,有些服务对象会寻找理由延长服务期限,有时还表现出倒退行为,很多已经解决的问题重又出现,等等,这种反应是( )。
简述教育政策与教育路线及方针的关系。
求助者有两种求助动机:执行性求助和工具性求助。前者是自己不做任何尝试或努力,只想知道答案或让他人代自己完成任务;后者是借助其他人的力量以达到自己解决问题或实现目标的目的。根据上述定义,下列属于工具性求助的是:
在需要恢复路由器密码时,应进入的路由器工作模式是
Nooneshouldbeforcedtowearauniformunderanycircumstance.Uniformsaredemandingtothehumanspiritandtotallyunneces
最新回复
(
0
)