问题 选择题

在一匀强电场区域中,有A、B、C、D四点恰好位于一平行四边形的四个顶点上,已知A、B、C三点电势分别为φA=1V,φB=4V,φC=0,则D点电势φD大小为(  )

A.-3V

B.2V

C.0

D.1V

答案

将BC四等分,标上四等分点E、F、G,则根据匀强电场中沿电场线方向相等距离,电势差相等可知,E点的电势为1V,F点的电势为2V,G点的电势为3V.连接AE,则AE为一条等势线,根据几何知识可知,DPAE,则DP也是一条等势线,所以D点电势UD=-3V.

故选:A

阅读理解

Microblog(微博) is used by more and more people in China. Do you know what it is? Microblog makes the people around the world to know each other better. It helps people to find the information that they need easier, also to get some information about the world they did not know before.

Many famous people are using microblog now, including singers, TV hosts and artists. Yao Chen once became the queen of microblog because her microblog has over 1.3million followers; Li Yuchun sent a microblog and got 11760 comments(评论) within 24 hours; Cai Kangyong, who is a famous TV host and famous writer in Taiwan, has 15143 more followers within 24 hours.

Why is microblog so popular? The most important reason is that it is convenient(方便的). People need not use too much time to write the articles to express their feeling. They can write at most 140 words, and then send it through computers or mobile phones onto the microblog. They can use it anytime, anywhere.

Many of my friends use microblog to share what they see, hear and think in a sentence or a photo with others. Also, they can follow their friends’ or their favorite stars’ microblogs. Microblog is very hot now!

Have you microblog today ?

根据短文内容,完成下列句子。

小题1:Microblog helps people to find ___________ that they need easier.

小题2:___________ is the queen of microblog.

小题3:Microblog is so ___________ that it’s becoming more and more popular.

小题4:People send their words through ______ or mobile phones onto the microblog.

小题5:We can use a microblog to _________ what we see, hear and think in a sentence or a photo.

名词解释