问题 实验题

(6分)为探究并联电路中电压的规律,实验室提供的器材有:干电池组(电压约为3V)、

电压表、多个小灯泡、开关、导线若干.

⑴用笔画线代替导线,在图(甲)中把电路连接完整,要求电压表测量灯L1两端的电压.

⑵电路连接正确后进行实验,某小组分别测出灯L1、L2两端的电压和并联电路的总电压,电压表示数相同,如图(乙)所示,其值为        V.根据这组数据,该小组得出并联电路中电压的规律.你认为实验的疏漏之处是                                

答案

(1)连图如下3分  (2)2.6 …1分 没有更换灯泡,多次实验…2分

题目分析:电压表连接在电路中时,要注意连接位置、量程和电流方向.根据指针位置读出示数,在实验中为了避免实验的偶然性,增加实验的可信度,一般最少做三次试验,同样的,利用相同的方法来研究.

(1)灯L1、L2并联,要测量灯泡L1两端电压,电压表需与L1并联,因为干电池组电压为3V,则选择0~3V量程.

(2)由图可知:因为干电池组电压为3V,选择0~3V量程,则对应的分度值为0.1V;根据指针所指位置可读出电压值为2.6V;利用实验得出实验结论的过程中,为了避免实验的偶然性,增加实验的可信度,换用不同规格的灯泡多测量几次并联电路两端的电压.才能进行归纳总结,这样得出的结论才更加准确.并联电路中的电压规律为:并联电路两端的总电压和各支路两端的电压相等

完形填空
完形填空。
       In America, when people say "man's best friend", they don't mean     1    person. Instead they are
talking about a lovely animal: a dog! These words show the friendship between people and     2   . Dogs
and other pets can give     3    to people's lives. Some people think of their pets as their children. A few
even leave all their money to their     4    when they die! 
       Animals can help people, too. Dogs can be taught to become the "   5   "for a blind (瞎的) person or
"   6    "for a deaf (聋的) person. Scientists have found that pets help people live    7   ! They make people
happier, too. Because of that animals are brought into hospitals for "visits".
       Americans hold "Be    8    to Animals Week", the first week of May. Pet shows are held during the
week. Even if you don't live in America, you, too, can do this. How? If you have a pet, take     9    time
this week to play with it. Remember to give it delicious    10 
      If you don't have a pet, be kind to animals around you. If you see a    11   dog, don't kick it or throw
things at it. Instead, just leave it alone, or better yet, make friends with it. If others around you do bad things
to an animal, try to   12   them. As people, we must protect animals who can't speak for themselves.
( )1. A. another 
( )2. A. persons  
( )3. A. sadness  
( )4. A. family  
( )5. A. eyes   
( )6. A. eyes   
( )7. A. alone  
( )8. A. Bad    
( )9. A. less   
( )10. A. food   
( )11. A. lovely  
( )12. A. help   
B. the other
B. people  
B. sad   
B. pets   
B. ears   
B. ears   
B. together 
B. Happy  
B. more   
B. meat   
B. little            
B. catch  
C. other   
C. plants   
C. happiness  
C. children   
C. hands    
C. hands     
C. shorter   
C. Nice    
C. no        
C. drink     
C. street    
C. beat   
D. others  
D. animals   
D. happy     
D. parents    
D. feet       
D. feet                           
D. longer  
D. Sad        
D. some       
D. milk       
D. home      
D. stop     
单项选择题