问题 实验题

如图甲是测量小灯泡电功率的实验电路图,图中小灯泡的额定电压为2.5V。

(1)若选用干电池作电源,至少要用      节干电池串联起来。

(2)下面是同学们在实验过程中出现的一些情况,请你分析出现这些情况的可能原因。

A、连接好电路,闭合开关后,看到电流表指针如图乙所示偏转:                          

B、将最后一根导线连好后,马上看到灯泡发光:                                                

C、连接好电路,闭合开关后,小灯泡不亮,且电流表有示数,电压表无示数:                              

(3)正确连好电路后,闭合开关,调节滑动变阻器滑片的位置,小灯泡正常发光,此时电流表示数如图丙所示.则小灯泡的额定功率为           W。

答案

(1)2;     (2)A.电流表“+”、“-”接线柱接反了      B.在连接电路的过程中,开关未断开  C.小灯泡处发生短路;  (3)0.6

题目分析:(1)由于小灯泡的额定电压为2.5V,所以电源电压要大于2.5V,用干电池作电源,至少两节干电池串联,使电源电压为3V;

(2)A.乙图中,电流表的指针反偏,说明电流表的正负接线柱接反;

B.将最后一根导线连好后,马上看到灯泡发光,说明在连接电路的过程中,开关未断开;

C.电流表有示数,可以排除断路的故障,小灯泡和电压表都不工作,则是小灯泡被短路,由于它与电压表并联,所以二者同时被短路。

(3)电流表的示数为0.24A,则小灯泡的额定功率为:

阅读理解

An 80-year-old man was sitting on the sofa in his house along with his 45-year-old highly educated son.

Suddenly a crow perched on their window.

The father asked his son, “What is this?”

The son replied, “It is a crow.”

After a few minutes, the father asked his son the 2nd time, “What is this?”

The son said, “Father, I have just now told you ‘It’s a crow’.”

After a little while, the old father again asked his son the 3rd time, “What is this?”

At this time some expression of irritation was felt in the son’s tone when he said to his father. “It’s a crow, a crow, a crow.”

A little after, the father again asked his son the 4th time, “What is this?”

This time the son shouted at his father, “Why do you keep asking me the same question again and again, although I have told you so many times ‘IT IS A CROW’. Are you not able to understand this?”

A little later the father went to his room and came back with an old tattered diary, which he had maintained since his son was born. On opening a page, he asked his son to read that page. When the son read it, the following words were written in the diary:

“Today my little son aged three was sitting with me on the sofa, when a crow was sitting on the window. My son asked me 23 times what it was, and I replied to him all 23 times that it was a crow. I hugged him lovingly each time he asked me the same question again and again for 23 times. I did not at all feel irritated, I rather felt affection for my innocent child.”

小题1: The underlined word “irritation” in the passage means ___________.

A.puzzlement

B.annoyance

C.patience

D.excitement小题2: Why did the old father keep asking his son the same question?

A.Because he developed a kind of disease.

B.Because he was so boring that he wanted to play a joke with his son.

C.Because he wanted to know whether his son was as patient as he used to be.

D.Because his son used to love playing this game with him.小题3: How old was the father when he wrote down this page in the diary?

A.35 years old

B.38 years old

C.45 years old

D.80 years old小题4:The reason why the father did not feel irritated when his son asked him the same question for 23 times is that _______________.

A.he knew his son was still so innocent

B.the father was more patient than the son

C.the father had already got used to this kind of situation

D.the father loved his son so much that he never got tired of doing this again and again小题5:What would the son probably say after reading the words in the diary?

A.“Sorry, dad. It’s all my fault to forget that.”

B.Nothing but felt rather ashamed.

C.“Sorry, dad. I shouldn’t have done that to you when I was such a young child.”

D.“Thank you, dad. I will do the same to my son.”

判断题