问题 问答题

在“研究凸透镜成像”实验中:

(1)在桌面上由左向右依次放置蜡烛、凸透镜和光屏.

(2)他在水平位置放置的光具座上安装的器材如如图所示,你认为装置中明显的错误的是 ______,调节方法是 ______.

(3)已知凸透镜的焦点为10cm,实验测量数据如下表:

物距像的性质
正立或倒立缩小或放大实像或虚象
25cm倒立缩小实像
20cm倒立等大实像
15cm倒立放大实像
10cm不能成像
8cm正立放大虚像
认真观察上表,你有什么发现(指出两点):

①______;②______.

答案

(2)装置中明显的错误的是烛焰,凸透镜,光屏的中心不在同一高度;

可以将凸透镜往上调,使烛焰,凸透镜,光屏的中心在同一高度;

(3)当物距为25cm时,即当物距大于2倍焦距、成倒立、缩小的实像;

当物距为8cm时,即当物距小于焦距时,成正立、放大的虚象;

故答案为:烛焰,凸透镜,光屏的中心不在同一高度;将凸透镜往上调;

当物距大于2倍焦距、成倒立、缩小的实像;

当物距小于焦距时,成正立,放大的虚象.

完形填空
完形填空。
     One day a man went to see his friend. His friend lived far away, so he took some bread   1   him   2   his
lunch.When he walked along, he thought, "My friend is sure to give me a nice meal and   3   to eat." He took
out his bread and looked   4   it, "It's so dry. What's the use of it?"   5   these words, he threw the bread on
the road. Later he   6   to a river. There wasn't a boat by the river. And he   7   to the other side of the river.
He hoped to have a boat to take him over, so he sat by the river and waited. He waited and waited   8   the
sun went down in the west, but he couldn't see a boat. He stood up and started   9   back home. Soon he felt
very hungry. He wanted very much to have something to eat, but he had nothing with him. Suddenly he saw
some dry, hard bread in the middle of the road. He  10  and began to eat.
( )1. A. at             
( )2. A. in            
( )3. A. good something
( )4. A. at            
( )5. A. At            
( )6. A. comes         
( )7. A. couldn’t go  
( )8. A. if            
( )9. A. went           
( )10. A. picked up it 
B. in             
B. of             
B. something good 
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B. By             
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B. can’t go     
B. until           
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C. with         
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C. for             
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C. couldn’t to go
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D. of               
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D. With               
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D. can’t to go     
D. so                 
D. goes            
D. picked it up    
单项选择题