问题 实验题

额定电压为6V的小灯泡,其正常工作时的电流约为0.3A。小明想测定这个小灯泡的额定功率:

(1)小明设计了如图甲所示电路图,并将实验器材连接成图乙所示的实验电路。同小组的小亮在检查时认为,实验电路中有一根导线连接错了,建议小明改接。

①请你在接错的那根导线上打“×”;

②另画一根导线,使电路连接正确。

(2)小明同学按照自己的想法改接了一根导线,闭合开关后发现灯泡发光较暗,电流表和电压表均有示数.任意移动滑片,电压表示数始终不变,具体原因是                                   。

(3)小明改正错误后,当变阻器的滑片移到某位置时,电压表的示数为6V,电流表的示数如图丙所示,则小灯泡的额定电流为              A,额定功率为                 W。

答案

(1)“略”(2)滑动变阻器同时接入下接线柱 (3)0.32    1.92

单项选择题
阅读理解

It’s not easy being a teenager(13至19岁青少年)—nor is it easy being the parent of a teenager. You can make your child feel angry, hurt, or misunderstood by what you say without realizing it yourself. It is important to give your child the space he needs to grow while gently letting him know that you you’ll still be there for him when he needs you.

Expect a lot from your child, just not everything. Except for health and safety problems, such as drug use or careless driving; consider everything else open to discussion. If your child is unwilling to discuss something, don’t insist he tell you what’s on his mind. The more you insist, the more likely that he’ll clam up. Instead , let him attempt to solve(解决)things by himself. At the same time, remind him that you’re always there for him should he seek advice or help. Show respect for your teenager’s privacy (隐私). Never read him his mail or listen in on personal conversions.

Teach your teenager that the family phone is for the whole family. If your child talks on the family’s telephone for too long, tell him he can talk for15 minutes, but then he must stay off the phone for at least an equal period of time. This not only frees up the line so that other family members can make and receive calls, but teaches your teenager moderation(节制). Or if you are open to the idea, allow your teenager his own phone that he pays for with his own pocket money or a part –time job

68. The main purpose of the text is to tell parents _____________.

A. how to get along with a teenager

B. how to respect a teenager

C. how to understand a teenager

D. how to help a teenager grow up

69. What does the phrase “clam up” in Paragraph 2 probably mean?

A. become excited            B. show respect

C. refuse to talk                    D. seek help

70. What should parents do in raising a teenager according to the text?

A. Nor allow him to learn driving or take drugs

B. Give him advice only when necessary

C. Let him have his own telephone

D. Not talk about personal things with him