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
2014-04-23
38
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/IbWO777K
0
在职攻硕英语联考
相关试题推荐
Alineinasongasks,"Doesanyonereallyknowwhattimeitis?"Thisquestioncouldeasilyapplytocalendars!Didyouknowth
AlthoughmostuniversitiesintheUnitedStatesareonasemestersystemwhichoffersclassesinthefallandspring,someschoo
ThemanwhoinventedCoca-ColawasnotanativeAtlantan,butonthedayofhisfuneraleverydrugstoreintowntestimoniallysh
Untilmeninventedwaysofstayingunderwaterformorethanafewminutes,thewondersoftheworldbelowthesurfaceofthesea
Insomeculturestheessenceofmagicisitstraditionalintegrity;itcanbeefficientonlyifithasbeen______withoutlossfr
PresidentCoolidge’sstatement,“ThebusinessofAmericaisbusiness,”stillpointstoanimportanttruthtodaythatbusinessin
Theexcessivehospitality______thelocalofficialsfailedtoleaveusassured.
ThemainimpressiongrowingoutoftwelveyearsonthefacultyofamedicalschoolisthattheNo.1healthproblemintheU.S.
Britain’semissionsofgreenhousegases,blamedbymanyscientistsforcontributingtoglobalwarming,havefallenby14percent
随机试题
磷酸戊糖途径的重要生理功能是生成
如果建筑物的有效年龄小于实际年龄,就相当于建筑物比其实际竣工之日晚建成,此时建筑物的经济寿命可视为从这个晚建成之日开始到建筑物对房地产价值不再有贡献为止的时间。()
热力网中加工简单、安装方便、安全可靠、价廉、占空间大、局部阻力大的是()补偿器。
QDⅡ基金合同、招募说明书中的特殊披露要求包括( )。
荀子认为学习的过程是()
IntheUnitedStates,itisnotcustomarytotelephonesomeoneveryearlyinthemorning.Ifyoutelephonehimearlyintheday,
在一个抽象类中,一定包含
在报表中,不能实现的功能是()。
Thelittlegirlgraspedhermother’shandasshecrossedthestreet.
InJanuary2009,duringthefirstweeksofasix-monthstayattheChildren’sHospitalofPhiladelphiaforleukemia(白血病)treat
最新回复
(
0
)