问题 填空题

假设地球带的是负电,自转一周时间为T秒,其中在赤道线上分布的电子数为1019个,那么由于地球自转在赤道线上形成的等效环形电流方向为______________(填自东向西或自西向东),等效环形电流大小为_________A。

答案

自东向西,1.6/T

题目分析:地磁的北极在地理的南极附近,由于地球绕地轴作自西向东旋转,故地球上所带电荷的运动形成了一个环形电流,根据安培定可知右手的拇指指向南方,则弯曲的四指的方向则自东向西,故环形电流的方向应该由东向西,

点评:由于地球绕地轴作自西向东旋转,故地球上所带电荷的运动形成了一个环形电流,而地磁的北极在地理的南极附近,故根据安培定可知右手的拇指指向南方,则弯曲的四指的方向则自东向西.

阅读理解

Last summer vacation, I volunteered to work at a vet’s(兽医诊所). There I saw a lot of dogs. Minnie was the funniest-looking dog I’d ever seen. Short thin curly hair covered her sausage-shaped(香肠形)body. Her eyes always seemed surprised. And her tail looked like a rats tail.

She was brought to the vet because her owners didn’t want her any more. I thought Minnie had a sweet personality, though.“No one should judge her by her looks,”I thought. Finally, I advertised Minnie in the local paper.“Funny-looking dog, well-behaved, needs a loving family.”

When a boy called, I warned him that Minnie was strange-looking. The boy on the phone told me that his grandfather’s sixteen-year-old dog had just died. They wanted Minnie no matter what. I gave Minnie a good bath. Then we waited for them to arrive. At last, an old car pulled up in front of the vet’s. Two kids raced to the door. They picked Minnie up and rushed her out to their grandfather, who was waiting in the car. I hurried behind them to see his reaction to Minnie. Inside the car, the grandfather held Minnie in his arms and stroked her soft hair. She licked(舔)his face. Her tail wagged(摇摆)around so quickly that it looked like it might fly off her body.

“She’s perfect!”the old man said happily.

I was thankful that Minnie had found a good home.

Suddenly, I saw that the grandfather’s eyes were a milky white colour—he was blind.

小题1:The last three sentences in the first paragraph tell us      .

A.how funny Minnie looked

B.how well Minnie behaved

C.Minnie was a beautiful dog

D.Minnie was dying小题2:Why did the writer advertise Minnie in the local newspaper?

A.Because he wanted to sell her at a good price.

B.Because he didn’t want her any more, either.

C.Because he wanted to find a family for her.

D.Because he wanted to have another dog.小题3:Why did the boy who called the writer want Minnie?

A.Because he loved all kinds of dogs very much.

B.Because he had seen Minnie and loved her very much.

C.Because his grandfather’s dog was too old.

D.Because his grandfather’s dog had just died.小题4:The underlined word“stroke”may mean      .

A.抚摸

B.拔

C.剪

D.揪小题5:Which of the following is TRUE?

A.Minnie wasn’t the type of dog the old man loved.

B.The old man couldn’t see how funny Minnie looked.

C.Minnie knew very well how to make others dislike her.

D.Minnie was like the old man’s dog which had just died

解答题