科目: 来源: 题型:
【题目】一种半导体材料称为“霍尔材料”,用它制成的元件称为“霍尔元件”,这种材料有可定向移动的电荷,称为“载流子”,每个载流子的电荷量大小为1个元电荷量,即q=1.6×10-19 C,霍尔元件在自动检测、控制领域得到广泛应用,如录像机中用来测量录像磁鼓的转速、电梯中用来检测电梯门是否关闭以及自动控制升降电动机的电源的通断等。在一次实验中,一块霍尔材料制成的薄片宽AB=1.0×10-2m、长BC=4.0×10-2m、厚h=1×10-3m,水平放置在竖直方向上的磁感应强度B=1.5 T的匀强磁场中,BC方向通有I=3.0 A的电流,如图所示,沿宽度产生1.0×10-5 V的横向电压。
(1)假定载流子是电子,A、B两端中哪端电势较高?
(2)薄板中形成电流I的载流子定向运动的速率多大?
查看答案和解析>>
科目: 来源: 题型:
【题目】短文改错
假定英语课上老师要求同桌之间交换修改作文,请你修改你同桌写的以下作文。文中共有10处语言错误,每句中最多有两处。错误涉及一个单词的增加、删除或修改。
增加:在缺词处加一个漏词符号(∧),并在其下面写出该加的词。
删除:把多余的词用斜线(\)划掉。
修改:在错的词下划一横线,并在该词下面写出修改后的词。
注意:
1. 每处错误及其修改均仅限一词;
2. 只允许修改10处,多者(从第11处起)不计分。
Dear friends,
It is real a good chance to have met all of you here. We have spent several precious weekend in learning in the English Club. Although we have been members for a short period of times, we have made a great progress. That is because we are all very actively and the activities are not only enjoyable and also helpful. Besides, the foreign teachers here work hard and try his best to make the activities lively and interested. I am very pleased to say that all of us greatly improved our spoken English so far. I am looking forward to see all of you again in the near future!
查看答案和解析>>
科目: 来源: 题型:
【题目】一理想变压器原、副线圈匝数比n1∶n2=11∶5。原线圈与正弦交变电源连接,输入电压u如图所示。副线圈仅接入一个10Ω的电阻,则( )
A.流过电阻的电流是20A
B.与电阻并联的电压表的示数是100V
C.经过1分钟电阻发出的热量是6×103 J
D.变压器的输入功率是1×103 W
查看答案和解析>>
科目: 来源: 题型:
【题目】短文改错
假定英语课上老师要求同桌之间交换修改作文,请你修改你同桌写的以下作文。文中共有10处语言错误,每句中最多有两处。错误涉及一个单词的增加、删除或修改。
增加:在缺词处加一个漏词符号(∧),并在其下面写出该加的词。
删除:把多余的词用斜线(\)划掉。
修改:在错的词下划一横线,并在该词下面写出修改后的词。
注意:
1. 每处错误及其修改均仅限一词;
2. 只允许修改10处,多者(从第11处起)不计分。
When I was a child, I spent more than ten years learn the violin. Therefore, I couldn’t understand "real music". After I graduated at high school, a friend of mine suggested that we started to learn the guitar because we all thought it was cool. I will never forget the day on that we went to buy guitars in the guitar store. There he saw a guitar player playing the guitar, which I really enjoyed. He became my the first guitar teacher. It took me such a long time choose a guitar among several wonderful model. Now the guitar is the most importantly part of my life and I practice it every day.
查看答案和解析>>
科目: 来源: 题型:
【题目】如图所示,开关接直流上灯泡的亮度______(填“大于”“小于”或“等于”)接到交流上灯泡亮度,说明线圈对直流电和交变电流的阻碍作用不同。
电感对交变电流阻碍作用的大小,用__________来表示,线圈的自感系数越大,自感作用就越大,感抗就______;交变电流的频率越高,电流变化越快,自感作用越大,感抗______,电感有______________的作用。
查看答案和解析>>
科目: 来源: 题型:
【题目】短文改错
假定英语课上老师要求同桌之间交换修改作文,请你修改你同桌写的以下作文。文中共有10处语言错误,每句中最多有两处。错误涉及一个单词的增加、删除或修改。
增加:在缺词处加一个漏词符号(∧),并在其下面写出该加的词。
删除:把多余的词用斜线(\)划掉。
修改:在错的词下划一横线,并在该词下面写出修改后的词。
注意:
1. 每处错误及其修改均仅限一词;
2. 只允许修改10处,多者(从第11处起)不计分。
In the past, I always think my little brother was very unpleasant, because he used to ask me some questions every time he did his homeworks. I felt as if I had been the smartest person in the world every time he accepted my explanations. Answered one of his questions, I often liked to say that he was too stupidly to solve such simple questions.
Last week both us received our report cards from our school. Unexpectedly, I got C’s, when he got straight A’s. To make things bad, all the day my brother screamed what foolish it was of me not to ask questions! I just sighed and had to admit that she was right. I have never made a fun of him since then.
查看答案和解析>>
科目: 来源: 题型:
【题目】某化学实验小组同学利用以下实验装置制取氨气,并探究氨气的性质(部分仪器已略去)。请回答:
(1)实验室制备氨气的化学方程式为______________________。
(2)用装置B收集氨气时,应选择氨气的进气口是________(填“a”或“b”),并说明选择的理由是________________________________。
(3)打开装置B中的止水夹c,若观察到烧瓶内产生了红色喷泉,则说明氨气具有的性质是________________、________________。
(4)为防止环境污染,以下装置(盛放的液体均为水)可用于吸收多余氨气的是________(填序号)。
查看答案和解析>>
湖北省互联网违法和不良信息举报平台 | 网上有害信息举报专区 | 电信诈骗举报专区 | 涉历史虚无主义有害信息举报专区 | 涉企侵权举报专区
违法和不良信息举报电话:027-86699610 举报邮箱:58377363@163.com