问题 多选题

如图A、B为两等量异号电荷,A带正电,B带负电,在A、B连线上有a、b、c三点,其中b为连线的中点,ab=bc,则(  )

A.a点与c点的电场强度相同

B.a点与c点的电势相同

C.a、b间电势差与b、c间电势差相等

D.点电荷q沿A、B连线的中垂线移动,电场力不做功

答案

A、A、B为两等量异号电荷,产生的电场关于AB连线的中垂线对称,则可知a点与c点的电场强度相同.故A正确.

    B、电场线方向从A到B,顺着电场线,电势降低,则a点电势高于c点的电势.故B错误.

    C、由于AB产生的电场关于AB连线的中垂线左右对称,又ab=bc,根据U=Ed可定性分析得出a、b间电势差与b、c间电势差相等.故C正确.

    D、A、B连线的中垂线是一条等势线,点电荷q沿A、B连线的中垂线移动时,电场力不做功.故D正确.

故选ACD

阅读理解

阅读理解。

     Liu Mei has a happy family. She lives with her grandparents and parents in Taizhou. Her father is a

doctor. He goes to work on foot every day. He is not very tall, but he is very strong. Her mother is a

teacher. She goes to work by car. She loves her students. Liu Mei's grandparents stay at home. In the

morning, they go to the park. In the afternoon, they drink tea with their friends. In the evening, they

watch TV and read newspapers.

     Liu Mei is a student in No. 2 Middle School. Her school is very beautiful. There are many tall

buildings there. She likes studying at this school. And she loves her family very much.

1. What do Liu Mei's parents do?

A. A doctor and a worker.            

B. A nurse and a teacher.

C. A doctor and a teacher.            

D. A teacher and a worker.

2. What is Liu Mei's father like?

A. He's very tall.    

B. He's very old.    

C. He's very strong.  

D. He's very happy

3. What do Liu Mei's grandparents NOT do every day?

A. Watch TV and read newspapers.    

B. Drink tea with their friends

C. Go to the park.                  

D. Go to work.

4. Which is true according to the passage (根据这篇文章)?

A. Liu Mei lives with her grandparents in Nanjing.

B. Liu Mei's father goes to work by car.

C. Liu Mei is a student in No. 2 Middle School.

D. Liu Mei doesn't like studying at her school.

5. Which is the best title (题目) of the passage?

A. Liu Mei's grandparents.            

B. Liu Mei's hobbies.

C. Liu Mei's family.                

D. Liu Mei's school.

单项选择题