问题 选择题

如图所示,通电直导线旁放一个金属线框且线框和导线在同一平面内。以下哪种运动方式不能使线框abcd 中产生感应电流?(    )

A.线框以AB为轴旋转

B.线框以ad边为轴旋转

C.线框向右移动

D.线框以ab边为轴旋转

答案

答案:A

题目分析:根据通电直导线产生的磁场规律可得:在以直导线上的点为圆心的圆上,r越大,磁场强度越弱,距离导线的距离相等,则磁感应强度一样,故可判断BCD中磁通量都发生变化,A中磁通量不变化,故A不可能产生感应电流,

故选A

点评:本题的关键是知道通电直导线产生的磁场的规律

阅读理解

阅读理解。

     "Cool" is a word with many meanings. Its old meaning is used to express a temperature that is a little

bit cold.  As the world has changed, the word has had many different meanings. "Cool" can be used to

express feelings of interest in almost everything.

     When you see a famous car in the street, maybe you will say, "It's cool. " You may think, "He's so

cool," when you see your favourite football player.

     We all maximize (扩大) the meaning of "cool". You can use it instead of many words, such as "new"

or "surprising". Here's an interesting story we can use to show the way the word is used.  A teacher

asked her students to write about the waterfall (瀑布) they had visited.  On one student's paper was

just the one sentence, "It's so cool. " Maybe he thought it was the best way to show what he saw and felt.

     But the story also shows a scarcity (缺乏) of words.  Without "cool" , some people have no words to

show the same meaning.  So it is quite important to keep some credibility (可信性). Can you think of

many other words that make your life as colourful as the word "cool"? I can. And I think they are also

very cool.

1. We know that the word "cool" has had                   .

A. only one meaning                    

B. no meaning

C. many different meanings              

D. the same meaning

2. In the passage, the word "express" means "                  ".

A. see          

B. show          

C. know        

D. feel

3. If you are                   something, you may say,"It's cool. "

A. interested in    

B. angry about      

C. worried about  

D.  unhappy with

4. The writer takes an example to show he is                   the way the word is used.

A. pleased with        

B. strange to      

C. worried about    

D. unhappy with

5. In the passage,  the writer suggests(暗示)  that the word "cool"                   .

A. can be used instead of few words

B. usually means something interesting

C. can make your life colourful

D. may not be as cool as it seems

问答题 简答题