问题 实验题

图1是利用两个电流表A1和A2测量干电池电动势E和内阻r的电路原理图。图中S为开关,R为滑动变阻器,固定电阻R1和A1内阻之和为10000Ω(比r和滑动变阻器的总电阻都大得多),A2为理想电流表。

(1)按电路原理图在图2虚线框内各实物图之间画出连线。

(2)在闭合开关S前,将滑动变阻器的滑动端c移动至__________(填“a端”、“中央”或“b 端”)。

(3)闭合开关S,移动滑动变阻器的滑动端c至某一位置,读出电流表A1和A2的示数I1和I2。多次改变滑动端c的位置,得到的数据为

在图3所示的坐标纸上以I1为纵坐标、I2为横坐标画出所对应的I1-I2曲线。

(4)利用所得曲线求的电源的电动势E=__________V,内阻r=__________Ω。(保留两位小数)

(5)该电路中电源输出的短路电流Im=__________A。

答案

(1)连线如图1所示

(2)b端

(3)如图2所示

(4)1.49(在1.48~1.50范围内同样给分),0.60(在0.55~0.65范围内同样给分)

(5)2.4(2.3~2.7范围内同样给分)

阅读理解

阅读理解。

       A young woman was walking through a super- market to buy a few things when she noticed an

old man following her around.  Thinking nothing of it, she ignored him and continued shopping. After she

got what she wanted, she went to the checkout line, but the old man got in front of her, "Pardon me," he

said, "I'm sorry if my staring at you has made you feel uncomfortable, it's just because you look like my

granddaughter, who just died recently (最近).  And I miss her very much. "  "I'm very  sorry," replied the

young woman. "Is there any- thing I can do for you?" "Yes," the old man said.

      "As I'm leaving,  can you say  ' Good-bye, grandpa' to me? It would make me feel so much better. " "Sure," answered the young woman.

      As the old man was leaving, she called out. "Bye-bye, grandpa!" When she stepped up to the

checkout counter, she saw that her total was $ 178.50."How can that be?" she asked, "I only bought

a few things ! " "Your grandpa said you would pay for him," said the clerk.

1. Why did the old man follow the woman and let_______. her say " Bye-bye,  Grandpa" ?

A. He wanted to steal her money.

B. She looked like her dead granddaughter.

C. He wanted to stare at her.

D. He wanted her to pay for him.   

2. According to the passage we can know that_______.

A. the young woman is a careless person

B. the young woman is as clever as the old man

C. the young woman was pleased to pay for the old man

D. the young woman didn't know the old man at all

3. Which of the following is the best title of the story?

A. A Kind-Hearted Young Woman

B. The Total Was $ 178.50

C. Bye-bye Grandpa

D. An Old Man and His Granddaughter

单项选择题