问题 填空题

如图所示是简易天文望远镜的内部结构,远处的物体经过物镜成一个的_____实像,落在目镜______的位置;这个实像经过目镜成一个正立、_____像,如果你想制作简易天文望远镜,没有现成的透镜,可以选用合适的________(选填“近视”或“远视”)镜片来代替.

答案

缩小  小于焦距  放大的虚  远视

题目分析:望远镜中物镜的作用是使远处的物体成倒立缩小的实像,这个倒立缩小的实像正好落在目镜焦距内的位置,目镜的作用相当于一个放大镜,这个实像经过目镜成一个正立虚像,因远视眼的镜片是凸透镜,所以想制作简易天文望远镜,没有现成的透镜,可以选用合适的远视镜片来代替.

点评:望远镜是由两组凸透镜组成的,靠近眼睛的叫目镜,靠近被观测物体的叫物镜,物镜的作用是使远处的物体在焦点附近成实像,目镜的作用相当于一个放大镜,用来把这个像放大.

阅读理解

阅读短文,回答问题。

     Some things can carry messages, for example, a sign at the bus stop helps you to know which bus to

take. Signs on the door tell you where to go in or out. Have you ever noticed that there are a lot of signs

around you and that you receive messages from them all the time?

     People can communicate on many other ways. An artist can use his drawing to tell about beautiful

mountains, about the blue sea and many other things. Books are written to tell you about all the wonderful

things in the world and also about people and their ideas.

     Books, magazines, TVs, radios and films all help us to communicate with others. They all help us to

know what is going on in the world and what other people are thinking about.

1. What can help you if you want to know which bus to take?

                                                                                                       

2. What do the signs on the door do? 

                                                                                                       

3. People can communicate in many other ways, can't they?

                                                                                                       

4. What can help us to communicate with others?

                                                                                                       

5. What do they help us to do?

                                                                                                       

单项选择题