问题 选择题

在探究凸透镜成像规律的实验中,当物体离透镜16cm时,在光屏上得到一个倒立放大的像;那么,当物体离透镜8cm时,在光屏上将(  )

A.能得到一个倒立放大的像

B.能得到一个倒立缩小的像

C.能得到一个正立放大的像

D.不能得到像,但可以透过透镜看到一个正立放大的像

答案

一物体在凸透镜前16cm处,在凸透镜另一侧光屏上能得到一个倒立放大的实像,所以,f<16cm<2f,即8cm<f<16cm;

此时若把物体放在距离透镜8cm的地方,即其处于凸透镜的 1倍焦距以内,故在光屏上不能得到像,但可以透过透镜看到一个正立、放大的虚像.

故选D.

阅读理解

阅读理解。

     Summer is almost over and school will start soon, Bill and his father go to a store for school things.

 They see all kinds of notebooks, rulers, pens and pencils. They also see this sign (招牌).

                                       The Light (灯) Writer

        Have a look at the new Light Writer pen.

        This kind of pen has a light in it.

        Now you can write in the dark (黑暗).

        You can have fun when you write.

        Light Writer pens come in three colors: black, blue and red.

        Anybody can afford our great LOW price of ONLY $1.59.

                                         BUY ONE TODAY!

1. Light Writer is the name of a kind of _____.

    A. book                

    B. sport                 

    C. pen

2. Why does Bill go to the store?

    A. He needs a new Light Writer.

    B. He needs to buy school things.

    C. He likes to go shopping.

3. The purpose (目的) of the sign is to_____.

    A. sell pens          

    B. sell lights                

    C. help kids have fun

4. What does the word "low"mean in Chinese?

    A. 浅的.            

    B. 矮的.                  

    C. 低的.

5. What can we know from the story?

    A. Bill wants to have fun when he writes.

    B. Bill makes the sign with his new pen.

    C. Bill and his father see a sign about a new pen at the store.

填空题