问题 实验题

电池组E的电动势为3 V,内阻不计;   

电流表A1的量程为0~10 mA,内阻约为80 Ω;

电流表A2的量程为0~500 μA,内阻为l000 Ω; 

滑动变阻器R1的阻值范围0~10 Ω,额定电流为1 A;

电阻箱R2的阻值范围为0~9999 Ω,额定电流为1 A,    

开关S,导线若干。

小题1:利用上述器材,用伏安法测阻值约为140 Ω的待测电阻Rx的阻值,请在图中所示框中画出测Rx阻值的完整电路图,并在图中标明各器材的代号。

小题2:实验中,将电阻箱R2的阻值调为3 kΩ。再调整滑动变阻器R1,使电流表A2的示数300μA,若此时电流表A1的示数9 mA,则通过Rx的电流是   mA,进而求出Rx的阻值是   Ω。

答案

小题1:如图所示

小题2:8.7,138

小题1:因为没有电压表,所以应该用小量程的电流表串联大电阻代替电压表,即A2与电阻箱串联,然后并联在待测电阻两端,因为滑动变阻器的阻值较小,所以应该连成分压式,A1连在干路上,测电流,电路如下

小题2:通过Rx的电流是Rx的阻值是

阅读理解

阅读理解。

     As we know, there are differences between western culture and Chinese culture. We can see 

differences when we pay attention to the words that are used. Let's look at the words about describing

animals. Most phrases in Chinese about the dog. For example, "a homeless dog", "a running dog", and

"a dog catching a mouse", have negative meanings.

     But in western countries, dogs are considered honest and good friends of humans. In English, people

use dogs to describe positive behavior. For example, "You are lucky dog" means you are a lucky person.   And "Every dog has its day" means _____. To describe a person's serious illness, they say "sick as a dog". The word "dog-tired" means "very tired". The words about animals are used in positive or negative ways

in different cultures. We can learn about many differences in cultures by comparing how certain words

are used.

1. The correct Chinese meaning about "a homeless dog" is "_____".

A. 猎犬

B. 看门狗

C. 丧家犬

D. 家养犬

2. In English ,people use dogs to describe positive behavior because _____.

A. they have different culture

B. they think dogs are honest and good friends of humans

C. they like dogs very much

D. dogs are very active

3. Which sentence is right to fill in the blank in the passage?

A. every dog will die one day.

B. each person has bad luck at times.

C. each person has good luck at times.

D. every dog has good luck at times.

4. Which of the following is NOT true according to the passage?

A. In English people use the dog to describe positive behavior.

B. Most phrases in Chinese about the dog have negative meaning.

C. We should pay attention to the words about animals that are used.

D. "Sick as a dog" is used to describe a healthy person in western countries.

5. What 's the best title of the passage?

A. Dogs.

B. Western Culture.

C. Chinese Culture.

D. Different Countries Have Different Culture.

单项选择题