某同学要测量一个由均匀新材料制成的圆柱体的电阻率ρ。步骤如下: (1)用20分度

题型:实验题

问题:

某同学要测量一个由均匀新材料制成的圆柱体的电阻率ρ。步骤如下:

(1)用20分度的游标卡尺测量其长度如图所示,可知其长度为________________mm;

(2)用螺旋测微器测量其直径如图所示,可知其直径为__________mm;

(3)用多用电表的电阻“×10”档,按正确的操作步骤测此圆柱体的电阻,表盘的示数如图,则该电阻的阻值约为__________Ω。

(4)为更精确地测量其电阻,现有的器材及其代号和规格如下:

待测圆柱体电阻R

电流表A1(量程0~3mA,内阻约50Ω)

电流表A2(量程0~15mA,内阻约30Ω)

电压表V1(量程0~3V,内阻约10kΩ)

电压表V2(量程0~15V,内阻约25kΩ)

直流电源E(电动势4V,内阻不计)

滑动变阻器R1(阻值范围0~15Ω)

滑动变阻器R2(阻值范围0~2kΩ)

开关S,导线若干

为使实验误差较小,要求测得多组数据进行分析,请在框中画出测量用的正确电路图,并标明所用器材的代号。

考点:实验:测定金属的电阻率
题型:实验题
阅读下面一篇短文,理解大意,然后从各小题的四个选项中选出一个最佳答案,使短文连贯完整。
One day before my final exam, my dad gave me a gift. It completely changed my life.
On that day I had a      with my friends and it was a difficult time with my studies. I was unhappy. Then I noticed the gift. I      it and saw a DVD inside. Its name was “THE SECRET” However, I was in no mood (心情) to watch it. I sat down to study, but the      in my life—the fight, the sleepless nights and my poor health…Everything came to my mind. I wanted an answer but I wondered      there was any. Just then, I saw the DVD again. May be it would be helpful. I      my DVD player. I had no words to describe the feelings I experienced while watching it. The moving (动人的) stories of human beings made me so moved that I wouldn’t      any of them.
Thanks to my father’s gift “THE SECRET”, I discovered     . Everybody has difficulties in their lives. The important thing is that you should be      enough to face them. Now I have started      my studies and my friends. And I’m in good health, too. I often hear people say, “Wow!      perfect life you have!”
小题1:
A.tripB.partyC.talkD.fight
小题2:
A.openedB.keptC.movedD.broke
小题3:
A.chancesB.problemsC.suggestionsD.mistakes
小题4:
A.whyB.thatC.ifD.how
小题5:
A.turned onB.looked forC.put awayD.paid for
小题6:
A.reportB.forgetC.thinkD.remember
小题7:
A.yourselfB.itselfC.himselfD.myself
小题8:
A.madB.braveC.sadD.weak
小题9:
A.being busy withB.worrying aboutC.getting on well withD.being afraid of
小题10:
A.What aB.WhatC.How aD.How .
题型:实验题

监理在监控变更实施的过程中,发现如继续按照变更后的方案实施,将可能造成更大的损失。这种情况下,监理单位首先应该______。

A.组织专家对变更做进一步论证,确定变更风险
B.建议建设单位组织召开专题讨论会,评估变更方案
C.通知承建单位废除变更后的方案,按照原有方案继续实施
D.通知承建单位暂停实施工作,等待进一步监理指令

题型:实验题

一般李的坐果率达到()即可丰产。

A.3%一5%

B.8%~10%

C.17%一20%

D.25%一30%

题型:实验题

什么是典型饲料配方?

题型:实验题

氨区应按照要求配备适量2%的()水或2%的硼酸水,并有充足的氮气储备。

A.醋酸

B.盐酸

C.硫酸

D.钛酸

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