问题 填空题

(1)①图甲的螺旋测微器的读数是______mm;②图乙的游标卡尺的读数是______cm

(2)在“描绘小灯泡的伏安特性曲线”的实验中,除有一标有“6V,1.5W”的小灯泡、导线和开关外,还有:

A.直流电源6V(内阻不计)

B.直流电流表0~3A(内阻0.1Ω以下)

C.直流电流表0~300mA(内阻约为5Ω)

D.直流电压表0~10V(内阻约为15kΩ)

E. 滑动变阻器10Ω,2A

F.滑动变阻器1kΩ,0.5A

实验要求小灯泡两端的电压从零开始变化并能进行多次测量.

①实验中电流表应选用______,滑动变阻器应选用______(均用序号表示).

②在方框内画出实验电路图.

③试将图中所示器材连成实验电路.

答案

(1)螺旋测微器的固定刻度读数为2.0mm,可动刻度读数为0.01×32.8mm=0.398mm,所以最终读数为2.328mm.

游标卡尺的主尺读数为11mm,游标尺上第4个刻度与主尺上某一刻度对齐,故其读数为0.1×4mm=0.4mm,

所以最终读数为:11mm+0.4mm=11.4mm=1.14cm;

(2)①I=

P
U
=
1.5
6
A=250mA
,故电流表选C.

因要求电压从零开始变化,变阻器用分压接法,应选小阻值的E.

②本实验中要求多测几组数据,故应采用分压接法;同时因灯泡的内阻较小,与电流表内阻相差不多,故应采用电流表外接法,故电路图如图所示:

③根据电路图连接实物图如图所示:

故答案为:(1):2.328,1.14

(2)①C,E; ②如图所示;③如图所示.

阅读理解

阅读理解。

     Now we’re always hearing about road accident, and when we’re in a car we try to drive carefully, but how many of us take the same degree of care in our homes? Any large hospital will tell you the number of

the accidents that happen in the home is almost the same as those on the road.

     One of the commonest and most dangerous causes of home accidents is wrong and careless use of

electrical equipment. People will continue to use a loose plug or pull out a plug without first turning off the

 power. In spite of warnings, one will carry an electric heater into the bathroom when he is going to have a bath. Sometimes one forgets to cut off the power before mending a lamp or something else. All this will

cause accidents. So the rule about anything that work by electricity is: Switch off before you touch

anything and don’t pretend you know when you actually don’t.

      If you’ve got children in the house, it's always best to keep medicines of any kind out of their reach.

Otherwise, they may be taken for candies or a new kind of drink. When there are older people living with you, you have to take particular care in a number of ways in order to make them safe and happy.

     Fire, of course, is always a risk. So, remember not to dry clothes in front of fires, or leave stoves in the middle of rooms where they can easily be knocked over. And don’t forget to keep the children away from fire. Smoking, too, may cause fire. So you’d better give it up. Safety first may mean a little more time and

care, but it may save you a lot of trouble.

1. According to the writer, we try to drive carefully in a car while __________.    

A. we take the same degree of care in our homes    

B. We don’t care much about the accidents in large hospitals    

C. We don’t pay enough attention to home accidents   

D. We seldom think a lot about the road accidents 

2. We can learn from the text that __________.     

A. people should never be allowed to carry an electric heater into the bathroom   

B. the improper use of the electrical equipment is the most dangerous cause of home accidents    

C. people should cut off the power first before using the electrical equipment    

D. both the children and the older people should be taken special care of at home 

3. It can be inferred in the text that our life at home will be much safer if __________.     

A. we know more about the accidents that happen in the home 

B. all of us give up smoking as soon as possible     

C. we take more time and care in our life  

D. we keep the stoves at the corner of the rooms 

4. The main purpose of writing the text is __________.    

A. to tell how and why home accidents happen   

B. to persuade people to get rid of bad habits    

C. to explain how to use electrical equipment   

D. to instruct people how to prevent home accidents

单项选择题