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
58
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.
Henry’s electromagnet was______.
选项
A、exactly like Sturgeon’s
B、an improvement over Sturgeon’s
C、more dangerous than Sturgeon’s
D、not as good as Sturgeon’s
答案
B
解析
本题是一道具体细节题。问亨利的电磁铁与斯特杰恩的电磁铁有什么区别。文章第二段指出,在美国,一位名叫约瑟夫·亨利的科学家改进了斯特杰恩的电磁铁,他用丝绸将铜导线进行绝缘处理。这样他便能够在铁芯上缠绕许多圈导线,而不会在线圈的匝间造成短路的危险。他的电磁铁可以吸起2 300磅的铁。因此,本题的正确答案应是B“亨利的电磁铁是斯特杰恩的电磁铁的改进”。
转载请注明原文地址:https://kaotiyun.com/show/d9XO777K
0
在职攻硕英语联考
相关试题推荐
Theamazingsuccessofhumansasa【C1】______istheresultoftheevolutionarydevelopmentofourbrainswhichhasled,amongoth
Theamazingsuccessofhumansasa【C1】______istheresultoftheevolutionarydevelopmentofourbrainswhichhasled,amongoth
ThehistoryofAfrican—Americansduringthepast400yearsistraditionallynarrated【C1】______anongoingstruggleagainst【C2】___
ThehistoryofAfrican—Americansduringthepast400yearsistraditionallynarrated【C1】______anongoingstruggleagainst【C2】___
Bartendersarerarelyshyaboutofferinganopinion.ButonarecenteveningattheFinboroughWineCafe,inbetweenpoursofBe
Heissucha______thathebuiltaporchforhishouselastsummerduringhisvacation.
Wemadeplansforavisit,but______difficultieswithcarpreventedit.
Woman:AreyougoingtoHawaiionyourvacation?Man:Notthisyear.Iambroke.Woman:Oh!Comeon.Question:Howdoesthewom
Britain’semissionsofgreenhousegases,blamedbymanyscientistsforcontributingtoglobalwarming,havefallenby14percent
随机试题
贫血是尿毒症必有症状,引起贫血的原因哪项是重要的
具有"斩关夺门之功",用于治疗寒积便秘的药物是
A.白虎汤B.清营汤C.犀角地黄汤D.当归六黄汤E.白虎加人参汤
有助于建立良好的护际关系的策略应除外
为落实淘汰落后产能政策,某区政府发布通告:凡在本通告附件所列名单中的企业两年内关闭。提前关闭或者积极配合的给予一定补贴,逾期不履行的强制关闭。关于通告的性质,下列哪一选项是正确的?
甲公司开发建设的某工业项目,土地面积为20000m2,2007年11月取得建设工程规划许可证,规划建设厂房5幢,食堂、浴室、办公楼各1幢,总建筑面积为25000m2。2008年6月甲公司取得了其中的办公楼和3幢厂房的建设工程施工许可证,总建筑面积为1650
从学生的实际情况、个别差异出发,有的放矢地进行判别教育,使每个学生都能扬长避短,获得最佳发展。这体现了_____教学原则。【】
IEEE802.8定义了______。
在项目管理器中,将一程序设置为主程序的方法是
Commutertrainsareoftenstuffyandcrowded,andtheyfrequentlyfailtorunontime.Asifthatwerenotbadenough,Tsuyoshi
最新回复
(
0
)