问题 选择题

在图中,A. B两图分别为测灯泡电阻 R的电路图,下述说法不正确的是(    )

A.A图的接法叫电流表外接法,B图的接法叫电流表的内接法

B.A中R >R,B中R<R

C.A中误差由电压表分流引起,为了减小误差,应使R<<Rv,故此法测较小电阻好

D.B中误差由电流表分压引起,为了减小误差,应使R>>RA,故此法测较大电阻好

答案

答案:B

题目分析:内接法即将电流表和被测电阻接在电压表两个接头之间,这样测得的电流完全准确,而电压则是电流表和电压表共同电压,用于电阻较大时。外接法则是将电流表接在电压表接头之外(即不是两接头之间的位置),这样测得得电压完全准确,而电流则是电压表和电阻的共同电流,用于电阻较小时,A CD正确,。

A中测量值为灯泡和电压表的并联值,R<R,B中测量值为灯泡和电压表的串联值R >R,B错误。

故选B。

点评:充分利用串并联电路的特点和性质分析电路问题。

阅读理解

One day a student went to see his teacher. He had been given an important position and now was coming to say goodbye to his teacher. The old man asked him how he would live among high officials. The student answered, “ I will be all right. I have prepared a hundred high hats, one for each official I will meet. I am sure I will succeed.” The teacher got angry on hearing this.  “What?” he cried. “Is this what ten years of my teaching has made of you? Nothing but flatterer(拍马屁的人)?” “Excuse me, honored(尊敬的) master,” the student  rose to his feet and apologized hurriedly. “But you have always been absorbed in(沉浸于) your studies and don’t know how vulgar(庸俗的) the world has come to be. There are few men in the world who are above flatterers like you.” “There is something true in what you said,” the teacher nodded, smiling with one of the student’s “high hats” on.

小题1:The student came to say goodbye to his teacher because_____________.

A.he had got hundred hats to sell

B.he had got a fairly high position in society

C.he wanted to see his parents in his home town

D.he moved away to another city小题2:The student would live among high officials by___________.

A.selling hats to them

B.making a hundred hats for them

C.flattering them

D.serving them小题3:The teacher was angry with__________.

A.himself

B.the society

C.his student

D.high officials小题4:The phrase “rose to his feet” means________.

A.stood up

B.kicked with his feet

C.became quite excited

D.raised his feet小题5:The teacher____________.

A.liked to be flattered as well

B.really knew nothing about the vulgar world

C.was in need of a high hat

D.was satisfied with the new hat

名词解释