问题 实验题

在“描绘小灯泡的伏安特性曲线”的实验中,使用的小灯泡标有“6 V 3 W”,其他可供选择的器材有:

A.电压表V1(量程6 V,内阻20 kΩ)

B.电压表V2(量程20 V,内阻60 kΩ)

C.电流表A1(量程3 A,内阻0.2 Ω)

D.电流表A2(量程0.6 A,内阻1 Ω)

E.滑动变阻器R1(0~1000 Ω,0.5 A)

F.滑动变阻器R2(0~20 Ω,2 A)

G.学生电源E(6 V~8 V)

H.开关S及导线若干

某同学通过实验测得小灯泡两端的电压U和通过它的电流I,绘成U-I关系曲线如图甲所示.

(1)实验中电压表应选用____,电流表应选用_____,滑动变阻器应选用________;

(2)在虚线框乙中画出实验所用的电路图;

(3)若将该小灯泡接在电动势为6 V,内阻为4 Ω的电源两端,则灯泡实际消耗的功率为________W.

答案

(1)ADF;(2)如下图(外接、分压);(3)1.89

题目分析: 从小灯泡的规格知,小灯泡两端电压最大值6 V,电流最大值0.5 A,为使读数尽可能地准确,以减小误差,电压表选A,电流表选D.要描绘小灯泡的伏安特性曲线,电压必须从0开始连续变化,所以要采用分压式电路,滑动变阻器选D,操作方便一些。

画出电动势为6 V,内阻为4 Ω的电源的U-I图(下图中的红色),则与小灯泡的伏安特性曲线的交点就表示了该闭合电路所工作的状态,此交点的横、纵坐标的乘积即为外电阻所消耗的功率P=4.2×0.45W=1.89W。

完形填空
任务型阅读(共两节,满分35分)
A Journey of Discovery
The Adventures of Huckleberry Finn by Mark Twain is one of the most famous American novels.
Published in 1884, it was one of the first novels in the USA written in common, everyday language. For example, using non-standard English, Twain wrote, ‘I haven’t got no money,’ to mean ‘I do not have any money’. In this way, Twain made his characters very true to life.
The story is told by Huckleberry Finn, called Huck for short, who runs away to escape his abusive father. At first, Huck goes to a small island in the middle of the Mississippi River. There, he finds Jim, a black slave who has run away to escape slavery. The two of them stay on the island for a few weeks and become friends, but they must leave because Huck learns that people are looking for Jim. They decide to travel on a raft on the Mississippi River to reach the Ohio River, which will take them north to a state that does not allow slavery.
During their journey, Huck and Jim visit many places along the river and meet many different people. Unfortunately, most of the people they meet are not good. For instance, Huck and Jim meet a family, the Grangerfords, who have been fighting with another family, the Shepherdsons, for so many years that nobody remembers how the fight began. While Huck stays with the Grangerfords, the fighting starts again, and several members of both families are killed. Lat6r, Huck and Jim meet the King and the Duke, two men who take control of their raft and make money by tricking people. During the confusion following one of these tricks, Huck and Jim escape with their raft.
Although the people Huck and Jim meet are bad, they are also funny. Mark Twain used humour to show readers the problems of American society in the t800s. More importantly, despite all of the bad things that happen to Huck and Jim, the novel has a happy ending for both of them. Jim gets his freedom because his owner has died and set him free in her will, and Huck learns that his father has died, so he is also safe.
The Aclventures of Huckleberry Finn is an adventurous and humourous story, and it teaches modern readers a lot about American society in the 1800s.
The passage
The passage ‘A journey of discovery’ is a brief (71) _______ to the novel The Adventures of Huckleberry Finn by Mark Twain, which (72)________ out in I884.
The novel
The Adventures of Huckleberry Finn, one of the most famous American novels, is an adventurous and humorous story. The novel was (73) __________ in America in the 1800s, when slavery existed. In the novel Mark Twain used common and everyday language to make his characters very true to life and used humour to (74) _________ readers the problems of American society in the 1800s.
The main
(75) _______
Huck fled his father and settled himself on an island in the Mississippi River, (76) __________ he met Jim and made friends with him.
(77) ___________ that people were looking for Jim, they decided to travel to a northern state that did not allow slavery.
During the journey, Huck and Jim visited many places and met many different people.
Though many of the people they met were not good, they (78) ____________.
Conclusion
Modern readers can learn a great (79) ____________ about American society in the 1800s from Huck and Jim’s adventures during their journey to (80) ____________
单项选择题