问题 问答题

(单选题)利用图中所示装置研究双缝干涉现象,下面几种说法正确的是(  )

A.将屏移近双缝,干涉条纹间距变宽

B.将滤光片由蓝色换成红色,干涉条纹间距变宽

C.将单缝向双缝移动一小段距离后,干涉条纹间距变宽

D.换一个两缝之间距离较大的双缝,干涉条纹间距变宽.

答案

A、根据条纹间距△x=

L
d
λ,将屏移近双缝时,使L减小,所以条纹间距△x变小,故A错误.

B、将滤光片由蓝色换成红色,使波长λ增大,故△x增大,故B正确.

C、将单缝向双缝移动一小段距离后,使L减小,故△x变小,故C错误.

D、换一个两缝之间距离较大的双缝,使d增大,故△x变小,故D错误.

故选B.

阅读理解

“My dear lady,” says Holmes. “You’re shaking. Are you cold? Do you want a cup of hot tea?”

“I’m not cold,” the woman replies, “I fear for my life!”

“We are here to help you. Don’t worry about anything. I don’t know you. But I know many things about you. For example, I know how you travel. You came to London by train. You also ride to the train station on a horse-drawn wagon(马车).”

“Why, yes. You’re right. But how do you know these things?”

“I see a return ticket in your glove. I see fresh mud(泥土) on the left arm of your dress. Now tell us your problem.”

“My name is Helen Stoner,” she states, “My mother and father are dead. I am living with my stepfather(继父), Dr Grimesby Roylott. He comes from a rich family. But they are no longer rich. They have nothing except a small piece of land and a big old house. We are living in the house. Dr Roylott is using my mother’s money for expenses(开支). Part of it was for my sister and me. It was for our marriages.”

Holmes is sitting in his chair. His eyes are closed. He is listening carefully to Helen’s story. He hears every detail.

Helen continues. “My stepfather has no friends. He fights with everyone. He is strong and gets angry quickly. Everyone is afraid of him.”

“He has no friends at all?” asks Holmes.

“No. He talks to no one except the gypsies(吉普赛人). They are poor people who travel from place to place. A band of gypsies is staying on our land right now.”

“Are you and your sister afraid of the gypsies?”

“My dear Mr Holmes. You are making me so sad. My sister is dead. That is why I am standing here in this room.”

小题1:Paragraph 6 beginning with “My name is …” is mostly about ________.

A.Helen’s dead sister

B.Helen’s trip to London

C.the house Helen lives in

D.Helen’s stepfather and the family小题2:What is Holmes doing while Helen is telling her story?

A.Walking slowly.

B.Listening carefully.

C.Standing sadly.

D.Writing quickly.小题3:Which of the following can best describe the gypsies according to the passage?

A.They are very rich.

B.They are afraid of other people.

C.They live on a horse-drawn wagon.

D.They move from one place to another.

单项选择题